Oh, well I've not personally built the $50 robot, but I've done photovores before using a Handyboard, which has a different development platform..
Regarding going around the house and not bumping into things, the source code might be slightly different, and you would probably have to change the sensors to a different kind, but I believe the $50 robot can be adapted to do that.
Have you managed to get the wheels of the robot to turn? You can try shining light at one or both of the light sensors and see if it makes a difference. I don't think the board will actually make any noise, but wheels turning will be quite noticeable if it happens.
If that doesn't work, then there is probably some error in either the software or hardware..
Edit: by hardware I mean connections and the like, I don't think the components themselves are faulty (that does happen, but the probability of that happening is lower)