1. Only buy items that are adequately pictured and described. You don't necessarily pay a premium price for items that are thoroughly and effectively displayed and you greatly reduce your risk due to defects that you couldn't see.
2. For little or no apparent reason, final bid prices vary wildly. Sometimes tools in similar condition and with similar function will vary by a factor of four or greater. For instance, a hand brace can vary from $20 to over $100 for two similar models for no reason or perhaps because one carries a certain name even though it is identical to another lesser-known brand.
3. Inspect items thoroughly. Some of the items sold are incomplete, missing essential parts, broken, worn out, chipped, cracked, and otherwise compromised. Even the seller may not be aware of an issue. Unless you are running a vintage tool repair shop, wait for the good stuff, or at least the stuff you know how to repair.
4. Consider buying from a reputable seller who guarantees their items.
5. Cheaper tools and disposable tools are usually better bought new. Things like chisels, spokeshaves, sharpening stones, router planes, files, screwdrivers, awls, knives and suchlike are often in poor condition, improperly handled or stored, difficult to correctly identify, damaged, missing parts, suffering from neglect and abuse and otherwise compromised. If you have lots of patience, or can combine shipping costs of multiple items, you might still be able to get a good deal on some of those lower priced and more problem prone items.
6. Some of the things you buy will almost certainly require repairs, reconditioning, new parts, excessive filing or dressing or sharpening, or otherwise be a general pain or worse, be useless or cost money to fix. For every $100 you spend, figure that you will have to spend $15-30 repairing or replacing problematic items. For people who don't do proper research, I would suggest this might run much higher.
7. Do your research. Know what you are buying. You should be able to look at the item you are buying and have a pretty good idea if it is a quality tool and if all of the parts are present. You can't do this if you don't know the components the tools is supposed to have.
8. Google is your friend. When you come across an unknown brand or a tool whose heritage or identity are in doubt, look it up. Someone, somewhere has probably written an article about just that tool.
9. Fortunately for us, the needs of collectors and users are generally quite different. Collectors are usually looking for rare stuff. Users are normally looking for the common stuff that everybody used.
10. I have gotten some pretty sweet deals on ebay. I have also bought a few "boat anchors."
Let me know how you make out.
Luke Townsley
UnpluggedShop.com