Actually the 1/8th buggy wheels are not that much bigger in diameter compared to the stock tires. Maybe an 1/8th inch and about the same with the 3.2" wheels and tires.

But the 1/8th buggy wheels are definately the cheapest solution for bigger wheels. I got mine from supra sales off ebay for $14.99 a full set already mounted and glued. But then you got the price of the 17mm adapters which I think is about $17.99 so you're lookin at a little over $30 for 1/8 tire setup.