That might be a good place to start, check on eBay. Things go pretty cheap from the earlier days. Then you can look at getting into recent stuff with autos and game-used (or nowadays photoshoot-used )
As for the brands, there are 2 currently (excluding Press Pass and Sage):
Upper Deck and Topps
There are basically 2 brands now Upper Deck and Topps. Different players signed with different companies. Upper Deck make nicer cards overall but it is harder to get the good hits out of a box and also Upper Deck has had some issues with card quality. Topps are getting better and are coming out with better stuff all the time. Basically u are better off decideing on what u want to collect ie, player, set, team and then take it from there. Hope this helps.