We need to figure out a better way to communicate this in our storefront so I'll reiterate it here: You can actually save yourself some money by buying armature pieces un-assembled in the Kits&Bits page. Just add the arm, leg, head, pelvis and torso type you want and you're done. For example if all you really want is a biped with digitigrade legs, you don't need to buy the entire biped and add those legs on top of it, you could simply buy those legs + arms + torso, pelvis, universal peanut and head and you're done. You can browse through all these different pieces here:
http://store.digitaldouble.net/collections/kits-bits
The other advantage of doing this is it allows you to pick exactly the arm, leg and head type you prefer.