I got a Troxel Liberty recently and I've been impressed with it how comfortable and decent looking it is for the low price. Very light and well vented.
Ovation helmets are pretty great schooling helmets and are usually around $100 or less in the US
The GPAs in Canada are close to $900 now :/
I have a GPA Speed Air Evolution and it keeps you much fresher than most helmets. It's around €350 though...