I highly recommend the original Nike hyperrevs. Due to their superior traction and ankle lock,all while retaining complete lightweight mesh construction. It's essentially a sturdy, breathable sock with good traction.
The seller is legit. There's an eBay money back guarantee if they do not come as described. If you pay through PayPal, you'll be all good. You shouldn't have a problem with the authenticity.
Based on my knowledge,these check out. They're either real, or the best replicas of all time. Based on the number of air holes on the toe box, and the shape of the rear of the shoe, you've got yourself a real pair of 750s.