Now that version 2 design is completed and verified to be working, I did a rough tally on the costs.  Assuming you need to buy all components, but already have all required tools, the total cost will come in at about $150.  If you already have components, this will obviously be lower (and honestly, who doesn't have a few ATmega 1284's hanging around!)

The single most expensive items are the servos and the XBee (especially since you need two XBees: one for the controller, and one for the robot).  The XBees can be substituted by any RF serial link, including the cheap eBay ones.  Bi-directional communication is highly recommended, but is not required.  If you don't support bi-directional communication, you can just program the Universal Controller to use the required defaults (enable analog sticks + slow down the analog sending rate).

Other ways to save costs would be to just use a perf board instead of ordering printed PCBs, a resonator instead of crystal + caps, and potentially using smaller bolts for the leg joints.

Personally, I ended up spending less than $60 for the new components required - most of what was used was already sitting in my parts bin.  (My parts bin is not particularly well stocked, either, so I would assume that most hackers could do this for a similar outlay).