I used to own ASM 38, the last Ditko issue, but I sold it for a pittance along with DD7, PPTSS1 and wolverine 1. I got it for 3quid at a convention when I was in my early teens, it had been bent over, that's why i got it so cheap, apart from that slight creasing it was in ok condition.
So the oldest one I now have is ASM 45, the second part of that Lizard story. I got that when I was very young, I would go to conventions back then and just buy any Spider-man comic that looked good from the illustration on the cover, probably only paid a couple of quid for it. It has a rip out of it's back corner though.
Next oldest is ASM 54, which is one of my all time favourite Spider-man issues, the one where Aunt May takes in Doc Ock as a lodger.
After that ASM 77, the one with the Human Torch and spidey fighting the Lizard, and then 96, the famous drugs issue. Again i got these when I was a kid at conventions, just based on the covers, not trying to buy antiques or anything, just looking for a good comic. I would have flipped out back then if they had published the Essentials books, as there were so many old Spider-man books i wanted to read but could not afford.
When I was about 5 yrs old, I had this colouring in book that was full of Spider-man comic covers from the early 70s, ie all the issues I missed cause I was born in 74. I used to look at those covers and imagine what the stories were about.
So, one day back in about 2004 i was walking around the town centre drunk off my ass, and happened to spot a Spider-man essentials book in a record shop(i had stopped buying comics, mainly buying music, so did not know these books existed), I flipped open the book and it had all the stories from that frickin colouring in book, and yes, it was thirty years later, but it was worth the wait. It was no7 of the EC.