I haven’t spent much one a single card. Overall I only own about 300 Magic cards. I own all the 8th Edition starter decks, 2 Mirrodon Theme decks, and about 5 random Magic boosters. Even with my small collection, I have all the land I will ever need.
The most I’ve spend on one card is probably about 2 dollars for Vedalken Shackles. It was a Fifth Dawn artifact that cost 3 but had the ability “2, tap: Gain control of target creature with power less than or equal to the number of Islands you control as long as Vedalken Shackles remains tapped.” I bought this the very first day it was released online and the card when up and up in value.
So how much have you spent for a card?