Breeders will be your best bet through basenji.org
, but if you're near a rescue (BRAT or other) and have time to spare….that may be a good route. The facebook page "Basenji puppies for sale" sounds sketchy, but there are actually some good breeders on there. It looks mostly like out of country options at first, but when litters are available I've seen plenty of US litters being advertized.
Petfinder is another route to go (but you have to be careful of scammers on there).
Google can be helpful just by typing in "basenji litter 2014" and researching whoever pops up. Some of them aren't responsible though, so you really have to do your homework.