Thanks to all the help on this forum, we have successfully completed the $50 robot. I wanted to post some pictures and a short video to say thanks and hopefully pass on any ideas for people building the $50 robot next.
We stayed pretty close to spec, but made a few variations. For power we opted for the battery pack and 9v combination. In the photos you will see a big old D battery. This is not powering anything, but rather weighing down the from end. You see every time the robot would bump into something, it would tip over, so this solution prevents that most of the time. Our servos did not come with the mounts shown in the tutorial so we improvised by cutting some scrap wood molding. Works great. We also wanted to follow admin's suggestion to mount the board properly, so some plastic spacers did the trick of nicely elevating the board and providing space for the battery pack. I was planning to Velcro the battery pack as Admin suggested, but my son suggested the rubberband method as it would make it easier to slide the pack out in our design. We did go with the nicer wire connectors. Following the wire connector tutorial and buying a pair of crimpers for the job. Otherwise, it is your pretty typical $50 robot.
We had our share of troubles along the way. This was our first time building a robot from scratch. But the forum here has been terrific to solve issues. Thanks again.
Here's a video