Downhill helmets? Not super cheap, and going to be hot in the summer. Why do you need full face? I don't know if I'd want to wear a hockey helmet. Besides looking like the "special" person on the pathway, they aren't optimized for the kind of impact cyclists experience. If I had to go full face it would be a mountain bike downhill helmet.
This is probably the best price you will find, doesn't look to bad.
https://www.mec.ca/en/product/5052-6...Cycling-Helmet