It depends on your situation, but it is usually less costly to lease. If you're a new customer then it is advantageous to lease a 622/211 since the first receiver (lease fee) is included in the price of qualified programming under the Digital Home Advantage (DHA) program. However, if your an existing customer and upgrade under the Dish'n It Up (DIU) promotion, you will be required to pay a $6 HD lease fee for your 622/211 in addition to a $5 SD fee or $6 HD fee for each addition (leased or owned) receiver on your account.
In my case, I had a $250 non-refundable lease upgrade fee already sunk into a 942...so I kept that receiver, and I purchased a 622 and returned a leased 811 vice pay a $299 non-refundable lease upgrade fee and commit to 18 months of programming. In a nutshell, I would have been locked into 18 months of programming, indirectly paying for installation I didn't need, and I would have had to pay an additional $6 lease fee each and every month.
Additionally, Verizon FiOS is coming to my area....probably another 12-24 months away from my neighborhood, but either way I'll be better purchasing since I can sell the unit or keep it for HD only...if ever then get rid of that stupid HD enabling fee.