I bought the trio - PHB, DMG and MM - as soon as they were available with a substantial discount, and resold them (for a few more bucks :p) as soon as i understood 5e was not my thing (same thing happened with 4e)... well, i suppose it still counts as 1 copy.
Birthright 19 + 1 = 20 (c'mon, everyone should try to pronounce Awnsheghlien at least once in their lifetime :p)
Blackmoor 21
Council of Wyrms 18
Dark Sun 20
Dragon Fist 16
Dragonlance 18
Eberron 22
Forgotten Realms 11
Ghostwalk 20
Greyhawk 22
Jakandor 21
Kingdoms of Kalamar 20
Lankhmar 21...