Ground Zero Games(GZG), Critical Mass Games (CMG) and Old Crow (OC) models take large chunks of my income with 15mm sci-fi. Of particular note are: Hammers Slammers OC for vehicles and GZG for figures; CMG Mercenary packs and the Protolene, and GZG Crusties - District 9 aliens.
If ylou ar after Post-apoc 15mm then The Scene are worth a look.