I strongly advise against buying from an unauthorised dealer if you plan to buy new. Even if they are legit, Monster wont honor a warranty claim if they break (assuming the seller doesnt include the original purchase receipt). I would suggest you try calling the onecall.com staff, and negotiate a reasonable price. I have heard of people getting the Turbine Gold's for $200, lowest I have seen is $180, and Turbine Copper's for ~$220. You will get the full lifetime warranty from Monster, since they are an authorised dealer.
As for the ones that look fake. the only real giveaway that I know is the taper of the tips, and mesh guard on the opening. the real ones curve and bubble out a little, the fakes have flat mesh that is recessed into the tip.