Now it has gone, it would be interesting to know which auction you were looking at, and to see if anybody wuld have had an opinion regarding the information and pictures in the sale, and an appraisal of purchasability based on the auction details.
My basic approach is to
Consider the seller - what they usually sell, how often, and the feedback they get
Consider the article - make and model reputation, prices they fetch in closed Ebay auctions; condition from pictures
Add in an overhaul cost to purchase price if you do not do the work yourself
Risk assess the financial stake - thinking what can be recovered by flipping it back onto Ebay if it does not suit you
Ask specific questions of the seller to further reduce risk of purchase
If after that I would want to buy (and it is not a BIN) then I consider the maximum amount I would be happy paying for it and set a snipe bid for that amount and forget about it. If someone is willing to pay more than me, they get it, otherwise I get it for a price set by someone else who wantd it.