10tacle :
Your best bet if you want to overpay for one (they are selling for $100-$150+ more than their MSRP when you can find one in stock): sign up for Auto-notify for the GPU you want on NewEgg and B&H Photo. And when you do get that email ding, you better jump on the order button like a cowboy drawing a pistol in the Old West because it will go fast. You aren't the only one getting said notification of being back in stock.
Overpaying that much for a 1070 is kind of silly though, when you can get a 1080 for close to the same price. : P
I wouldn't consider jumping on one at all if it's priced around $500. Just get a GTX 1080 in that case, since those currently start at around $550, for 20-25% more performance. A GTX 1070 priced significantly more than $400 is a GTX 1070 not worth buying.