(Also glee-killing: AMa 95)
I very rarely need calculus in my work, and so over time tend to forget an embarrassing amount of it. Three or four times I've decided to remedy this by rereading these books (although once, for variety, I used Spivak instead of Apostol). Of course, I always end up forgetting again.
The latest time I did this I tried to burn it in deeper by doing every exercise from Volume I, and every calculus exercise from Volume II. I probably should have kept my solutions and put them on the net. They might have been useful for people who are using these books for self-study.
My originals from the late '70s have physically not held up well. Loose pages, and the cover pulling away from the spine, and stuff like that.
There is an international paperback edition. The publisher does not sell it in the US, but numerous independent booksellers outside the US will sell and ship to the US, and several independent booksellers in the US import it. Same content as the US hardback, just thinner, a bit coarser, paper.
The US booksellers selling the imports typically sell them for about $18 per volume (including shipping). You can shave a couple dollars off that buying from an Indian seller, but personally I'd rather pay a little more to avoid a credit card transaction with someone who is under a completely different legal system just in case something goes wrong.
abebooks.com and biblio.com are good places to go for this kind of thing.
I bought mine used for maybe $5 each from some foolish upperclassman who thought he was done with calculus.