I used a toaster oven and a hot plate to cook exclusively for several years when I was a broke student. Heres how I achieved a crispy crust in a small oven.
First, get a 12 inch pizza stone (they are awesome and you can use them to cook anything that you want crispy! Like fries, wings, and pizza!)
Second, preheat the stone under the broiler setting as high as it will go.
Third, place the pizza on the stone under the broiler and let it cook to your desired level of "doneness." The residual heat from the stone will cook the crust nice and crisp, while the broiler will melt the cheese and cook/heat any toppings.
I should note this is for fresh pizza (i.e. "homemade," not frozen pizza) which is what I am assuming you are making? Also this works best with a thin crust!