I honestly doubt you can find it on amazon or ebay. There ain't shit out there to buy. You'll see the occasional marauder suit or whatever, but there aren't any basic troops or bugs or what have you.
nobody played it back in the day, let alone now. I heard the rules were solid, but the models were of very poor quality. Managed to pick up a few of the exosuits myself and was pretty disappointed. They look way cooler in the tiny pictures. Still look decent painted up, but what doesn't?