The Amazing Spider-Man [1963 series]
30 issues [1966 - 1997]
35, 195, 213 - 222, 224 - 232, 365, 389 - 395, 419
The long-running series created by Ditko and Lee that went to #441 a few years back before someone decided it would be cool to do a new #1. I was never much of a Spidey fan as a kid, and didn't keep most of the issues I had, but I did like that run in 1981-82 where Denny O'Neil and then Roger Stern wrote the book, with some solid art by John Romita Jr. and Jim Mooney. Tried it a few times after that, but it never really tuck, though I did like some of the writing in that run I kept by J. Marc DeMatteis in #389-#395, but the combination of the art and the crossovers kept me out of that, and I'll probably get rid of those someday. #419 I think I got free somewhere, and #365 has some stupid hologram cover, but I picked it up for a quarter since it has some John Romita art.
Most of my back-issue buying for the series has been satisfied by reprints, although I did decide to pick up one heavily beaten up copy of #35 a few years back, I think it was about $2 and looks like you'd imagine a $2 copy of Spider-Man from 1966 would look like, just to have one copy where I could compare the printing to the reprints.
Prices on them are out of my interest range, but I wouldn't mind reading more of the O'Neil and Stern written stories, maybe when ESSENTIAL SPIDER-MAN gets up to there in a few more volumes.
#35, of course, with Ditko at the top of his game.
#217 - #218 have one of my favourite O'Neil stories, with the Sandman and Hydro-Man getting all muddy (though O'Neil did better in his annuals with Frank Miller)
#229 - #230