Not sure if anyone is still looking for a pair of salmons, but I saw these on the Bay. Can't vouch for the seller though.
http://www.ebay.com/itm/Rare-NIKE-Air-Tech-Challenge-IV-Premium-SNEAKERS-Agassi-TENNIS-Pink-SHOES-New-10-/122433110662?hash=item1c81950286:g:gWkAAOSwmgJY5Vr1
Saw these on the Bay. Great deal and I would jump on them if I hadn't already doubled-up.
http://www.ebay.com/itm/nike-air-tech-challenge-iv-black-White-Dark-Grape-Fireberry-844606-015-Sz-9-/182500354799?hash=item2a7dde6aef:g:uoIAAOSwsW9Y0-4t
If you are still looking for a pair of ATC IV then Sneakersnstuff has a couple sizes (7, 8.5) for $91. Great deal from a very reputable site.
http://www.sneakersnstuff.com/en/product/24791/nike-air-tech-challenge-iv?utm_source=AdRoll&utm_medium=facebook&utm_content=Dynamic&utm_campaign=nf
Just scooped the Black ATC2 US Opens for $220. Thanks for the head's up!!
Been on a buying binge for ATC the last year or so and have actually never seen these ones. Is this a good deal? Seems to be.