28″ is a fairly common DL, but if you need Left Hand, not so good. Best bet for LH cam is AT Classified Ads Everything Left Handed.
You need a ZX cam
First place to check is all the local Mathews Pro Shops. Pricing on new cams varies from shop to shop, region to region. Many dealers also keep a selection of cams for bows, and now that the Z7X is discontinued they may want to let some go or might even swap out your cam with one of theirs.