I just canceled my 13 year service with Dish and was not under contract.
I can verify that it is $17 for each receiver and for that you get a shipping box and a UPS label. They will want you to return the receiver, the remote, and amazingly they also ask you to remove the LNB & switch from your dish and send that back too. The boxes also contain literature that 1. Warns of extremely high charges if you don't send this stuff back and 2. A flyer saying they are willing to do almost anything to have you sign back up and offers up some discounts for a 2 year contract.
There is no room in these boxes for more than one receiver. In my case I sent back a 622 & a 612 and it cost me $34 + tax. They subtracted the remaining credit on my account so I owe them about $11.
Furthermore, they also had a record of two old receivers that I owned back from the days when you bought your receiver, and they indicated they would be sending a separate envelope and request that I deposit the smart cards from those receivers and send those back as well.