I guess you don't even need a houseboat to live on the lake. We walked down to the fishing pier at Mesquite Bay last Tuesday.

http://www.fws.gov/refuge/Havasu/activities/fishing.html

There was a couple living out of their suitcase that had a blue tarp tied to the railing as a windbreak and will probably be there until the park rangers run them off.

I think there are equivalent homes that are a little bit cheaper than LHC in Fort Mohave or Bullhead City, Seems it's more of a sandy desert environment and the wind blows a lot there so you'd deal with more dust. Of course, there's always Needles, CA which is on the lake also, but it's sort of a dying town because the BNSF is cutting back operations there. It wouldn't be my choice but you might save a buck on a house.