Yes, you can "buy" (which really means lease at the same rate that D* gives you). You can then self-install and call to activate the receivers. I did this as I needed 4 HD/DVRs and 3 other receivers. Their basic free install does not cover wall fishes or attic runs or other complicated installs, which I needed and only 4 receivers.
So I ordered from a website provider who drop-shipped the hardware (cheaper than D*'s price), I installed them per my specs (wall fished, attic runs, extra cables, dish mount etc.) and then called to activate once I had good signal. You need to be able to know how to run the right kind of lines and obtain a good signal to do this - but if you can, it gets you setup the way you want.