The main issue is that the chips from the S7 and Avalon 6 are going into miners that are still NEW - no way are BitMain or Avalon going to willingly undercut their own miner sales right now. Try again in a few months.
SP50 may or may not actually exist, but Spondoolies seems to have decided to follow BitFury and KnC into the "big industrial sales only" market.
B-Eleven (Lktec/BW.com) unit doesn't appear to exist yet, or is still just in prototype. Same situation as Bitmain/Avalon, too new to be willing to undercut their miner sales for a while.
Innosilicon is a wild card, they've tended to sell chips starting close to or at the same time as their miners came out - but their next-gen chip appears to not be in full production yet.
21etc - see Bitfury, "mass orders only" or buy their light bulbs, err, Bitcoin massively overpriced not-really-a-miner boxes.
No clue what's going on with SFARDS, but their dual-mining chip is the worse of both worlds at current pricing and performance IF it's actually available for sale.
Talk to Sidehack about the issues a WELL KNOWN DEVELOPER has had in trying to get anything current-gen for his small projects.
Well said