Where i can find black leather outfit or pants like those celebrities wear?

some ppl tell me its so old fashion .. but alot of celebrites and music starts wear it and they look y !! i mean those leather outfits like in Alexandra Burke wore in her music video "Bad Boys" or those wore by christina aguliera in her last music video "Not my Self Tonight" ?? i really wana wear it ! any online store u knw have them ?? thnx