I purchased mine on Ebay for around $50. It is absolutely perfect. Took me years to find one that was "segmented" like the original. Mine has a controller box so you can either slow down or speed up the lights, I had the kit professionally installed on my black 2004 Mustang GT convertible ...

I have the Knight Rider talking Kitt as well, and it's one of the few toys that I kept from childhood. I wouldn't part with it for anything ! On that note, I do have two other original KR toys, one is the Michael Knight figure (from Kenner) that came with the KITT, I have an extra for sale, and also...