Kim Kardashian -- I'm So Popular in Miami, I Need More Real Estate

Kim Kardashian is in desperate need of an upgrade -- hitting the streets in Miami yesterday to find an even bigger home for her beachfront clothing boutique ... to accommodate its exploding popularity.

Sources tell TMZ, the Miami D-A-S-H store (below) has become so successful, it can no longer cater to the massive flux of customers coming and going on a daily basis ... so Kim wants something a little roomier, scoping out possible new locations herself.

Kim's not messing around either -- we're told she's in the market for retail space that's around DOUBLE the size of the current D-A-S-H store ... not bad.