I've been racing 1/8 scale buggies for quite a few years now. I've raced Ofna, Kyosho, and GS. Right now, if you're looking for good bang for your buck, check out the GS Storm Pro. You can pick up the chassis for less than $350 (comes with all the performance parts you're going to need for quite a while - thickest shock towers I've ever seen too). The kit builds easily (I have 2 of them - my primary car and my back-up).

Since it doesn't come with an engine, you can go with whichever engine you choose (like the new fantom 21 you mentioned).

I've done some serious abusing on my racer, and I've only sheared 2 bolts on the front suspension.