ORIGINAL: HerrSavage
For a sensibly priced buggy engine with a great reputation, I personally would go with a Werks B6 (or even B5 for more grunt.. - and less money..) with 2058 pipe and a couple of plugs, and leave 50 bucks in the bank..
But yeah, there are tons of good options - including pipe for under €400.. Argus, Alpha(Z852 or S852), Go GXII, Orion, Werks B5 or B6(or even B2 for short tracks..), OS XZ-B, Arrow, a cheaper Novarossi or RB...
or my modified Argus... $225.00 and more powerful then anything you could buy stock off the shelf at any price......