Paying more than £1 for a record, especially new ones or rare ones that I really want. I optimistically thought that buying something I liked on vinyl would give me the best sound. No. It has ended up in the stupid situation of where I have Dark side of the moon, a record I don't even really like on (fake) cassette £10, annoying as the not fake is supposed to be pretty good, CD £10, oldish Vinyl £20 (needs a clean££), Remastered SACD £20. The SACD sounds a bit better, probably due to the remastering, but have only listened to it once, compared to about 5 mins of the others.
I have 3 copies of Kraftwerk the mix, Cassette 50p, new vinyl £20 and CD £2. They all sound the same???
I once had a (charity shop) copy of "living voice" Mussorgsky pictures at an exhibition on vinyl, a truly excellent recording, which I stupidly got rid off the second time I got rid of all my records. Eventually tracked down what I though was the same thing on discogs from the US £35. Damaged record, unlistenable. Now have the SACD which is pretty good, still miss my original version.
For no particular reason I wanted a copy of Graceland on vinyl. Eventually got (given) a new copy £22, sounds like it is played through a cheap midi system. I could go on and on.