A flea market is not an auction. I asked, what's the difference if I purchased an item for $100 at a flea market or if I bid $100 for the same item on ebay? I still paid $100 and was happy to get it.

You then try to change the scenario to the effect that how about if the seller at the flea market only asked $50 for the item...

Scott; the flea market seller could have said "take the d@mn thing off my hands for $5 ... because I couldn't get $50 for it for the last year and a half!" Of course I would have given the flea market merchant $50 ... or $5 ... or whatever other figure under $100 that you hypothetically present.