I agree prices have increased greatly yrs ago I sold a fixed I had built up (531 frame and forks) and have regretted it ever since , so Iv been on the lookout for a decent frame in my size that I could build up.
So I found one on
eBay , the seller advertised it as seat pin MAY be stuck ,,, my arse , it bloody well was ! Anyway it looked as if it was stuck at a useable height for me so I bid on it and won , in the end I got a 531c frame with two brakesf fitted ( shimano 600) looks nice and it's the rightish size , it cost me 49 quid and a tenner in fuel to pick it up ,which prob sounds quite dear to some but they are hard to find and I've got a few bits lying about I can use them to build it up and use it , and even sell it once built up lol , but I tell u what it'll not b an eBay bargain , il have to buy a few bits ( wheels and crank , had all the rest) but even so all told I think itlstand me 150 for a quality bike that's worth ( going by eBay prices ) at least 300