the only open faced SA helmet i'm aware of, is this one: http://www.bellracing.com/public/index/product/detail/205/ they go for about $200, which really isn't bad for a full sa rated helmet.
Pyrotect also makes an open faced SA rated helmet. You can get them new for 100-150 online. Racequip makes one in that price range as well
it's a helmet, it was cheap, it fits without hurting - that's about it. Peltor or Stilo for the next one
i have never worn a helmet as comfortable as a peltor. they are well worth the extra money. i will also second the votes for the pyrotec and g-force brain buckets. they get the job done and wont break the piggy bank.