You didn't specify where your family is in the US.
I always think that the best place to look for the best deals in the US is in the greater metropolitan region of Los Angeles and because of the proximity, down to the greater metro San Diego region (and as far north as into Santa Barbara County). There seems to be the highest concentration of, well, everything, in this region, and motorycles, being part of everything are abundant here.
If you still cannot find what you want, or really want a good comparison, then search north into the greater metro areas of San Francisco, too (within a 2 hour commute of the city which will really give you access to hundreds of thousands of bikes California-wide, from the Mexican border to north of San Fran). You should have no problem registering the bike at your relatives' address being a US citizen, I would think.
(BTW-this is searching the various Craigslists.org cities, recycler.com , and cycletrader.com for the various regions of California, then expand nationwide)