I'd been searching for a comprehensive list of all the titles that fall into these series. The lists on Wikipedia are fine, but I was wondering about the covers. (Fantasy, SciFi)
Someone has already done the footwork. Here are the Fantasy Masterworks and the SciFi Masterworks.
(though, they seem to be missing the hardcover-only SF editions, such as A Canticle for Leibowitz)
These are British editions. I don't plan on collecting them all, that book monkey on my back is already the size of a Mighty Joe Young, but I have some of these and would like to cherry-pick some more.
With the ISBN numbers, I was able to find a bookdealer on AbeBooks who got me these books even cheaper than ordering (and shipping) from Amazon.co.uk, so I might try that again. Need to be sure though, with the ISBN, so I don't end up with a different imprint.