I found myself ordering a movie that was released in 2006. When I tried to find it on blu-ray, it was either out of stock, or 50 euros for a copy (which is insane for me). Finding a standard DVD is not a problem, but the Blu-ray is rare as hell. I ended up finding a "good" deal on ebay (around 20 euros with delivery). But while I'm waiting for it, I begin to think isn't it just too much? I usually stop myself from buying even a 4K movie for a similar price, but in this case I thought that if I'll let it go, I won't find a better deal in the future. But I don't see how can I pay more for that.

What's is your limit or breaking point in similar situations? Do you have any regrets from letting go a deal or buying for unreasonable price?