Re: how many cards do you own?
I guess I've been playing for about a year.
I have 5472 plant cards and 5416 zombie cards. I've never spent any money on the game and I've never crafted a card (or recycled a card) except for the hero quests of course.
My collecting strategy has been to build up gems and then buy 10-packs (or 60 packs back in the day when that wasn't a cash only thing) and then when I have nearly 4 copies of every legendary to use gems to get the legendary or event cards I'm missing by using the "complete strategy deck" option. I've often completed strategy decks I have no interest in using just to get the cards and sometimes even if I don't really want the cards (Hippity Hop Gargantuar, ick) because I like collecting.
This is a lot harder to do today with ad views worth less and 60 packs not available...