Need Help W/ Direct tv & dvr's

Hi, I have Direct TV S/D and want to upgrade to H/D. I refuse to pay the 199.00 (LEASE) fee. What I need to know is, can I purchase a DVR (aftermarket) type and receive the transmission from direct TV? I know that I will have to pay the 7.00 a month fee for the service but that is far cheaper than the lease fee that I lose regardless of my returning the equipment If I change companies. Help on this would be greatly appreciated. Thanks Gene.