
If the conversion is what *you* want in *Your* car and your not planning on selling it on anytime soon then i'd say go for it the price seems not too bad, I'd still ask around other local places though see what prices they'd give me.
But as topher said if your not going to be keeping the car for quite a few years to come, it really doesnt add much to the resale value and deters your 'average' car buyer from purchasing your car (Not everyone wants a pocket rocket) so your really not going to get your moneys worth.
Just my opinion.