Ever wonder if you got a good price for that collectible you just won on Ebay, or... are you nervous about how high to bid on an antique item up for sale?  Let's say you are looking at a Roseville Futura "four ball" vase.

Let's assume you know WHAT you are bidding on (or won) and you already know how to search for equivalent/comparable items, either through inspection of current auctions or by viewing "completed" auctions. 

An additional trick is to inspect the "bid history" of the item you are checking out, whether it be the item you're bidding on (or just won), or another "comparable."  From there, click on the "feedback" number for any participant in the current (or completed) auction you are looking at.  On the "feedback" page, click on the active (i.e., blue text) item number for any recent transaction. This brings up the completed auction. (Use the browser's "back" button to return to the "feedback" page to look at other transactions.)  What you are looking for are bidders who are very active in buying and selling items similar to the one you are interested in (i.e., heavy hitters)

In the case of my example, does this person buy a lot of Roseville, or antique pottery?  For good prices?  Better yet, does this person SELL a lot of Roseville?  Did any of the people bidding on "your" piece also bid on (or win) an identical or similar piece from a previous auction?

The idea is to find out if you are/were competing against a "heavy hitter," and to determine what the "heavy hitters" were willing to pay for the same item in another auction. 

If you won an auction and the underbidder(s) were notorious for buying and/or selling the same line of antique, then you should feel good about your purchase.  Similarly, if you are checking out a completed auction for a comparable item that closed out at $1000, where the last action by a recognizable "heavy hitter" came at $600, then use their action (or lack thereof) as a guide where to draw the line on  your future decisions. 

Good luck!