You can’t just use a DOT helmet at a track where they check helmets. The helmet has to be Snell rated M2010 or better.
It doesn’t matter how low it cost, if the helmet has the Snell rating it’s just as good as any other helmet with the same rating. Things that raise the price don’t always raise the safety.
Some brands are round shape (Bell) some are football shaped (Shoei). If you find the shape and size you like in a certain brand at the store you can then find the same brand with a Snell rating on line and it’s a good bet it will fit.