I'd go with a 10S setup and a MGM 12032 ESC for starters. Pick the biggest neu you can find and aim for about 40K rpm. That'll probably run you around $1,000 right there, and you're just getting started.
Whats the max voltage (or close to max) you should run on the Neu 1.5d and what about batteries can it handle a 6s lipo? Also does anyone have an answer to the question about when they will be back in stock?