I love my Scorpion EXO 700 helmet. It was only $160 (got the dark silver one, the ones with designs are $20 more I believe). The helmet is very comfortable, quiet, has many vents so I don't stay hot, the shield replaces very easily, and it is both DOT and snell approved. I believe a former engineer at either Arai or Shoei helped design the helmet, not sure the details but you can read about it on their website
www.scorpionusa.com (just for the record I am not affiliated with them
just very pleased with the helmet) It is an awesome value for an awesome helmet.