Desiigner: Look at Me Now!!!

Desiigner was a nobody 6 months ago ... but all it took was one big hit and now he's the king of Bev Hills.

The "Panda" rapper hit up Saint Laurent on Rodeo Drive and happily dropped $600 on a pair of shoes ... then made a quick exit with an assist from some massive hired muscle.

Being 19, rich and famous ... doesn't suck.