There is no point in buying packs from the secondary market unless you get them for under 3$ each.
You won't have any chance at promo card, you also won't have any chance for any of the 13 subsequent airdrops. Also, there will only be 2 more million packs to sell before they become available without any vouchers at 4$ each. And those packs that you will be able to buy will be eligible for future airdrops.
So you are paying twice the money for something that is less valuable.
I wouldn't be surprised to see Dr Blight at 500$ and 2500$ for the gold foil.

Another thing, you are saying that $4 x 50 = $100.
I think it would be more like 200.