How much $$$ to go fast?

I don't know of any turbo kits for less than 2k. But if you get a larger displacement (or stock) engine with a stock stroke, then add a turbo, you can have huge amounts of horsepower with less trouble than buying carbs, increasing stroke, splitting the case, adding this and that, etc...
At the same time, Vujade is on the right track. Go to aircooled.net and look under the technical section for "How to Get the Most out of VW Engine." Very honest and up front ways to make your engine powerful. It will also tell you whats easy or hard, and what is worth the money and work.