you can research pedigrees at this site:
http://www.pedigrees.zandebasenjis.com/search.html
I know that names and such may not mean much to you at this point in your basenji knowledge, but "show quality dogs" generally have LOTS of dogs with CH in front of their names in their pedigree. And the farther back in the pedigree the less that Championship counts. Ideally, you also want lots of dogs with performance titles, but you don't find a lot of performance titles in basenjis other than coursing titles. And, IMHO, for the price quoted on one of the websites you posted, I'd expect a show quality dog with lots of health testing. (Of course prices on either coast, tends to be more than prices in the middle of the country.)
I'll give you one of my dog's pedigrees for example.
Jet the trying is Jerlin's Saint or Sinner. So if you put in Sinner in step two of the zande website, you'll see Jet's name as #5, so you can click on the Pedigree with links button. In his pedigree, you will notice a lack of Fanconi status, but his birth (over 16 years ago) way predates any of the fanconi testing. His pedigree is light in the performance area, but given the time frame of his parents, they predate most performance sports other than obedience. But, you have to go back to a great g'mother to find a nonchampion.
for more health testing, you can go to
offa.org
and put in the dogs' registered name. you may have to play around with it as some kennel names have an apostrophe and sometimes that gets omitted for some reason.