Heh, I didn't catch the 722K reference either. No doubt they want you to call so that someone with a 722K doesn't order a USB dongle or someone with a Hopper doesn't order the MT2 plug-in module. Either way, what does Dish do, point you to companies like Dish Depot ?
I buy my adapters on Ebay and cut out the middleman. Brand new dual OTA adapters can be had for about $50 with free shipping.