Most hackable, cheap commercial robot?

[Cannon00]

What would be the best robot to modify for autonomous activity that's currently on the market and is a biped?  Would it be possible(read not overly difficult) to connect an Axxon to the Robosapien or isobot, and feed it commands from there?

[SmAsH]

I think i may have seen something like that before, but check out the BRAT chassis mounted with an axon by airman00. Plus there is SoR biped engine code already written!
http://www.societyofrobots.com/sor_biped_engine.shtml
But, take a look around google and you'll probably find something similar to what your doing.