This might be dense but, you are saying you want to buy individual cards you can resell for $50 or more? So you are looking for NICER single cards?
The buying in bulk phrasing makes me think something else.
for example a:
2011 Steve Young topps Super Bowl XXIX Legends Medallion 126/137 Champions Ring
wouldn't really interest you...
but a:
Jared Goff 2016 Panini Playbook Armory Rookie Tag 8 Patch/GLOVES #13/25
might interest you?
Check out my ebay listings and see if you like any of them and I'll get you a price.