careful. I have asked and as of yet no one is willing to say the 21.0 remote will work with any receiver except the 222k and 722k receivers.
Additionally the 21.0 remotes are balky. They do not learn all types of devices.
Before spending the money, I'd check thorughly to see if the 21.0 remote is compatible with the 612
Should work fine, although I have not tried it on my two 612s. I am running one 21.0 on an older 622--at it works there. I used the remote 21.0 on the 622 so I could control an Akai HDTV that could not be controlled by the older remotes. Worked well.
And yes, you can buy it direct from Dish for about $25. Just don't let the CSR talk you out of it. Their remote guide says it only works with 222k or 722k receivers. But that only means that it takes those "k" receivers to be able to do all the two-way remote functions.