Edwin - Yeah, I too built the 8-ton halftrack as a wee lad back in 1978 or so! Like you, I had a blast building it.
Bish - I get Modelkasten tracks from online retailers in Japan. We rarely see any AM tracks here at my LHS. Unfortunately you Brits get taxed to death when you buy stuff from overseas.
Gamera - I'll be tackling this kit right after I get the M3 Stuart done.