For reference, my setup and costs have been thus:
First, the stuff you need to make the engine perform well and make the kit worth the money:
64cc Malossi: $160
Leo Vinci HM: $95
Jets and crap: $20
And the other stuff I have that makes it a little more worth while:
Malossi Multivar: $80
TOP crank: $50
So figure $250 for the bike and $350 for performance parts, I'm in $600 plus I guess $60 for the Pirelli and the NR51. I think thats it. Anyway, not too bad in my mind for a rippin moped. I'll put gears on it eventually and that should keep me satisfied for a while.
I havent run the Polini 64, but Colin tells me it's quite similar to the Malossi one, and I can vouch for the power of the Malossi. Still have a few miles to go before I go WOT on it, but the low end power is crazy, even jetted like 6 sizes too rich and running 16:1. I can't wait to open it up and see what it'll do.