I bought a set of those nnbs 17s (your top pick) for $50 last fall, flipped them for $350 
There are deals, you just have to check every day. I literally saw the ad about 20 min after the guy posted it, drove over there 20 min later and scooped them

There are deals, you just have to check every day. I literally saw the ad about 20 min after the guy posted it, drove over there 20 min later and scooped them