Your best bet is scouting ebay and the forums when people put their collections up. I have seen some very cheap SST stuff.
Now the majority of it will have to be converted from the standard bugs. On ebay it might go two ways, it will either get cheaper because it is less useful... or more expensive because of the higher demand.
How I see it, certain units will become 'rarer' than others, these will be more than say, a warrior bug box.
Something less useful like the missiles box will go cheaply though. :?