Any brand which has passed some proper safety standard would have a sticker on it claiming that this product is made upto this particular standard...
Such as the guy at vohra autos sowed me an autocross style helmet of Malaysia... it had such a sticker, but that was not DOT or snell standard, a local Malaysian standard maybe...
I'd recommend u to spend some time online and see which cheapest helmet u can get i.e. DOT approved.
Stretch ur budget a lil bit and i guess u'd be able to find one... 7-8Ks maybe?
EBAY etc