D'Angelo Russell -- Rocks $2K Louis V Backpack ... For Dodgers 1st Pitch

L.A. Lakers rookie D'Angelo Russell is already taking advantage of his NBA paychecks -- droppin' $2k on a designer Louis Vuitton backpack ... that he rocked to Dodger Stadium.

Russell threw out of the first pitch Monday night ... and despite the fact his mechanics were rough, dude fired a strike ... unlike other NBA stars including Paul Pierce.

Nice job, rook.