Perhaps give some thought to the small fleet of training rifles. All AR, all identical, price, number? There'll be a very high liklihood that these weapons will have enormous wear-and-tear on them. You'll want high quality, but not so high that the price breaks you. Also, folks will tend to buy what they've just trained on, so consider what it is that you'd be happy selling them.
Oh, and the Kel-Tec Sub2000 is REALLY COOL. Maybe add one of them to the fun list?