I'm going to use the miniatures from Rebellion to play "Star Wars Assault on hoth" from west end games. they are nearly perfect! but one small problem. I need about 1/2 more of each ground unit to make it work.

is there any way to get more miniatures without buying a second game? if not I will likely just use the standees that Assault on hoth came with.

eBay maybe but unlikely. Otherwise, as you said, buy a 2nd copy, again, look ebay for a (cheap/damaged) copy?