The kit is about $9k, which IMHO is not too bad considering the engineering that went into it. I think they will sell plenty of them.
I am a 500 fan too, but I am going another route to get my dream bike. A couple of years ago I bought a ’97 KX500 for $1100* and an ’03 KX250 for $2100. I sold the flimsy stock 500 frame for $500 and the 250 engine runs well, so I will sell it once I have some time – hoping to get around $750 for it. So for around $3K (not counting farkles, suspension rebuild, etc.) I will have a steel perimeter frame power valve 500 that I expect will spank a T500, which has no power valve.
I am hoping my 500 will be my next MX bike after I do a few races on my ’97 KX250. I’ve been putting in some laps on my 250 and man, it is fun riding a two stroke again.
* KX500s are going for a lot more than that these days