Cast you hunt further then UK. We lived in Hawaii and fond our Basenji in N.Z. Cost was $2,000 but a lot of it was for air fare. He was worth all of it.
I would also look on Petharbor and Adopt-A-Pet. It can be difficult to find one under 1 year of age. You might have to go farther in your search or perhaps raise the age to 2 years.
Jennifer
http://www.coloradobasenjirescue.org/adoptable.shtml
Co basenji rescue has several young-ish dogs looking for homes. And those basenji/terrier mixes are adorable!