There was something posted years ago about cooking clay in a microwave. It was done in water. The results were so-so, but if that's what you're trying to do, I would say that it would be safe enough to use with food. The deal with the fumes is that they collect on the oven and over 400 degrees, they're toxic. So with a home oven, they next time you cook at 400 degrees, you start burning off toxic fumes. It won't kill you or even send you to the hospital; it's like pollution - it's just adds to your life load of toxins. The sides of the microwave don't heat up, so you shouldn't have that problem. I'd still wipe it down.
Sherry's advice is good. My most expensive purchase was a convection toaster oven from Craig's list for $35. I actually tried to spend more on one, but couldn't find one that didn't spike (you want consistent heat). I ended up with a B&D convection toaster oven, used, instead of an expensive new one and it works fine. Not as well as my old $20 one, but c'est la vie.