cheap is no good. you will want at least a 150 dollar helmet. look for the DOT and Snell m2000 rating. i think that snell m5 rating is the latest but im not sure
You could try garage sales if there are any where you live. when the kids move away or get sick of the sport you can sometimes find helmets that have not been used much.usually you can get a helmet for 5 or 10 dollars.