Looking for a used roller can be tricky and take more work. But I would only consider them if they have pictures! You can always tell how well the other person treated their stuff. If it looks real beat up and dirty, I would move on and keep looking. Used r/c cars are a lot like used real cars. You can be dealing with some one else's problems. I would ask what all is included in the deal and pictures only. How long they have had it and if they raced or bashed with it. Most nitro buggies and truggies are now available to be converted. So after you chose one, look on the web and see what's available. Here are two websites that can help:
http://www.rc-monster.com/
http://www.teknorc.com/index.php?osC...89d4a352a44307
Like said before I would go with either the Castle Creations Mamba Monster Max or Tekin.
http://www.castlecreations.com/
http://www.teamtekin.com/
Those are both race worthy and have a ton of thread's and info in this forum. But keep in mind that this route can be more expensive up front than nitro. But in the long run can be cheaper than nitro i.e constantly buying fuel, glow plugs etc. Hope this helps and keep us posted on your upcoming purchase.