Collecting in a relatively narrow area of interest, namely American bikes, I seem to have become friends with a bunch of folks with very similar interests. I'd like to say that is possible to deal with integrity with them and still buy more darn bikes and parts and tools than you can ever possibly use. We all seem to have done this over the years.
I will often counsel with these folks as to what think of a bike or similar object even when I know it is something they would like to own (an awful lot of folks now own bikes I have outed to them). If they tell me they are intending to bid on it, I'll just ask up front how badly they want it and how high they are willing to go. If they say something like $800 and I want it $1100 worth I'll just tell them that if they get overbid at that point I'll come in myself. Sometimes I am already high bidder on something, but I can live without it and a buddy will call or write and ask how high I am going.I have never been screwed in this process by a friend, yet. Sometimes a bike will have some really hard to find part that I need and I'll tell them if they want to lower their cost somewhat I'll buy the part if they get it, this may well give them some added flexibility.
If I get the item and don't care to keep it, I just automatically feel any of these folks that wanted it has first dibs on it.
In other words, we find that bidding on this stuff need not be cut throat. I think mature collectors are well aware that when all is said and done it is only a darn bicycle or part or whatever and that we are all bulging at the seams already and some other cool object will appear in a matter of days and it might be good not to be broke when that happens.
I think folks get too worked up over a lot of this stuff, after all, nearly anything will come your way eventually without you having to take the low road in any dealings.
Friends are a heck of a lot more important than things.
But I still find it hard to sleep the night before a new bike is to be delivered, I guess I'll just never grow up
Lansing, Mi USA