I haven't had anyone refuse to sell me 45s (except for a few times I've gone out on record buys and the chaps wanted too much for not-that-great records, so I made them a lowball offer which they passed on), but it brings a couple of stories to mind.
Speaking of loads of records, I'm sure some of you have been to Bill's in Dallas. If you haven't, it's an experience. I was there about 7 years ago before he moved to a new location, so I don't know what the store looks like now. Nothing is priced, so you have to go up ask Bill what he wants, and the price is the price to my knowledge. After 2 hours of having a rummage, I chucked it in. I saw a few bits, but just didn't want to mess about with going up there with items.
I was at the Wembley Record Fair 5-6 years back and saw a chap trying to beat up a dealer on an item (a videotape). He threw it on the ground, broke it into a million pieces and said "now no one is going to have it!"
Finally, I host a record show in the states. There's this chap who used to come up to me all the time and say I have a record for a certain price and would ask me to justify why I had it for a different price. I would try to explain the condition might be different, they might have paid less than I did to acquire it, etc., but I finally ignored him instead.
It's amazing!