There are plenty of online auctions these days. Some are specialist auctions, some are general. Some are open to everyone -- anyone can sign up and sell their stuff. For discussion, I will use eBay as an example. It is the biggest of the online auctions, with an incredible range of bidders. It is also a good general auction and a supportive community. And most other auctions share many of eBay's features.
Finding a good price
You may already have a very good idea of what kind of stamps you're looking for. Old stamps from Austria maybe, or U.S. Air Mail stamps, or just stamps showing Marilyn Monroe. If you just want a big box of stamps, or to buy someone else's whole collection, that's good too.
Find the Stamps category, and search for "Austria" or "Air Mail", or whatever you collect. You will probably see a list of matching entries come up, in all price ranges, with all kinds of quantities, pictures and descriptions.
Stamp collecting as a hobby has very well organized catalogs. So we should be able to find out the approximate value of the stamps we want to buy. While it is true that the real value of a collectible is how much a collector is willing to pay for it, it bothers me seeing some buyers paying way too much for common stamps. It can't be a good feeling when you've spent $10 for a stamp and your friends tell you it's only worth a dime.
Online auctions are catchy. It's so easy to bid on the things we want. We can even get emails when we're outbid by someone else, and a lot of bidders can't stand this. Here are some tips for keeping your cool.
Look for lots where the seller provides the catalog value. These values are not absolute, but they are how the values of stamps are compared in our business. When you see the catalog value, it can help you decide how much you want to pay for an item. For most of the stamps in the world, if you look hard enough, you should be able to find them for sale at between half and full catalog price. Don't let an online auction rush you into paying too much.
If the seller does not provide a catalog value, and you don't have a catalog handy, then you may get stuck paying $5 for a lot that's only "worth" $1. Why risk it? You might find the same stamps in another lot a week later, with a proper catalog value to help you place a more informed bid.
For "box lots" or collections, it's a bit different. If there's no estimated catalog value provided, it's hard to guess what the actual "value" will be. So, what's it worth to you? You can think in terms of how many cents per stamp you're willing to pay. So if you see a lot of 500 US commemoratives from the 1970's, don't just bid $50 out of the blue -- think that maybe they're worth 5 cents each to you, which gives you a bid of $25. I saw a lot of very early Turkish stamps a while back, hundreds of them: the starting bid of $3000 looked insane at first, but if you're familiar with these stamps, this was only $10 each, which was a great price. Always figure out what you're willing to pay per stamp, it's a great way to keep your bidding under control.
If a collection does have an estimated catalog price in the listing, it's a little easier. Most collections sell for 10% to 30% of the catalog price; this is because the catalog price is a retail price, and collections are "wholesale" deals. Bulk purchases are always done at lower than retail prices. You can set some basic rules for yourself. If I see someone selling Iceland at under 10 cents per stamp, or under 25% of the catalog price, that's a good deal. You may feel that 75% of catalog is a good deal for Iceland stamps. Figure out what works for you. Always compare the current bid to the estimated catalog price and see if the price makes sense to you.
Finding a good seller
Once you have studied the current bids on a lot, it's time to look at the seller.
You should look closely at the pictures provided, and read the whole description of the lot. The most responsible sellers will describe the condition of the stamps, provide photos or scans of the stamps, and explain their shipping charges. If there's no picture, forget it. There's no telling what you'll get. If the shipping cost is outrageous --like $3 for a couple of stamps that shouldn't cost more than 49 cents to mail -- don't bid. Some sellers simply don't understand our postal rates. You don't need that headache.
You should check to see what kind of payment the seller will take. I've had buyers get annoyed at me for not taking American Express cards, when my listing clearly says that I don't take credit cards. The sellers set the terms of the transaction, and you need to follow their rules. If a seller doesn't have the equipment to handle credit cards, that's the end of it. Almost everyone will take cash, checks or money orders. There are some nice online payment services now. I have used Paypal and Billpoint; they handle credit card payments online, and both are easy to use.
Check the seller's feedback if you want to get an idea of their past performance. If you see any negative feedback, check it out. Not every negative feedback means that the seller can't be trusted: sometimes things get lost in the mail, and there are customers who are never satisfied with anything. But if you see more than a few negatives, maybe you should avoid that seller and look at someone else's lots.
After a while, you will probably find some sellers that you trust. You can actually search EBay for all lots from any given seller, and you can bookmark these pages. Then, whenever you need stamps, you can see if your favorite seller has them; then look at the everyone else's lots.
Bidding & Winning
Once you've placed a bid, do not go back and bid again. Don't get sucked into it. Stick to your budget. If you get outbid, don't worry. Similar stamps will probably be available again soon enough, if not right away. If you're patient, and spend your money wisely, you will end up with more stamps in the long run.
If you have the winning bid, you will receive an email from EBay, then an email from the seller providing shipping info and where to send payment to. Send your payment promptly, and your stamps should show up in your mailbox soon. Leave feedback about the seller if you get the time; they will probably leave feedback about you. If you send your payment within 14 days of the lot closing, most sellers will be happy, and most will ship your stamps within 7 days of receiving payment.
If you have problems with any transactions, Ebay and other auctions all have an area to go for tips on how to resolve disputes. Don't just fire off a negative feedback and expect it to fix the problem. Email the seller, and try to be reasonable. If the seller is totally unreasonble, then negative feedback is the next step.
Out of about 1000 transactions on online auctions, I've only had a few that had problems. Most of these were solved easily, only a few payments or lots ever got lost. Maybe 30 lots that I sold were never paid for by the buyer -- all I can do after a few email reminders is shrug and relist them. One recurring problem is buyers who did not read the descriptions of lots and then complain about them. Don't be in a hurry to place bids. Read the descriptions, look at the pictures, and don't bid if you don't want what you see.
The online auctions are a marketplace of unprecedented scale and availability; it's like having access to all of the biggest stamp shows, year round, 24 hours a day. They can't replace the person-to-person feel of going to a real stamp show or stamp shop and talking to real people, but the online auctions make a wealth of stamps available to everyone.