Based on the seller's feedback and amount of Go Pro3's already sold (64), and the fact that its located in LA/Cali, it could be legit. According to most negitive reviews, they have shipped the wrong item multiple times without a refund and some have gone months without their item cause they said it wasn't in stock.
Don't think its worth the risk and no mounts to save $150.
Also note that this is one of their most expensive items sold. Everything else sold averages around $30-$40. Could be one of those money grab and let the negative reviews disappear due to the high volume of items sold (not really effecting their current rating... probably by 0.1)
I noticed something else. 87% of the negative reviews in the past year occurred within the last 6 months.