Does it matter which version of a game you get?

Currently looking at the possibility of taking up the game.

I see you need black or white for the base version of the game - does it matter which, i.e. exclusives etc? Same with SS/HG?

I'm not sure if cost is going to keep me out at this moment in time (due to my job need to ensure I'm 100% legit) but want to work it all out first! Really wish this was something pkmn offered themselves!

If anyone has any suggestions of where might sell relevant games cheap too I'm all ears.