Well, first off, I'm going to assume the bike in question is the MC Rumble. It is definately a nice bike, and somewhat rare, so you won't be like every other kid, riding a kona. The price for the frame depends a lot on how hard it has been used. While, as the guy above me suggested, getting a complete used bike off of ebay/pinkbike is nice, you have to be really careful, as sometimes bikes with serious flaws will be sold. Since you're buying it in person, you can hopefuly inspect the frame before you buy it. When you're looking for anything to be wrong with the bike, look for several things.
1) Check all welds for cracks, especially around the headtube. Breaking your frame sucks. Breaking your frame and having it break your neck sucks even more.
2) It is an alluminium frame, so check for any deep scratches/gouges.
3) If it is still built up when you go to check it out, make sure the size of the bike feels right for you. No matter how great the bike is, if it doesn't fit you to your liking, you won't get the full performance from it.
Finally, one last caveat, if you don't already have some of the parts needed to build up a bike, getting them can be a hassle and very expensive. Some parts can be gotten used, but you will likely spend 3-4X the cost of the frame on parts. Hell, my friend's wheelset costs almost double the cost of his frame.
