Directv Cards
Yes, the card is dedicated to your receiver ONLY. You cannot take a card from one receiver and use it in another unless you contact Directv.
When my receiver needed replaced several months ago Hughes service people told me to keep my old card and they would send a replacement receiver. When I called Directv to activate the new receiver I had to go through a bunch of hoops so that my old card would work in the replacement receiver. (I kept getting wrong card display on my tv)
So yes, I suppose you could buy a receiver from ebay but be aware you will have to call Directv to have it activated to work with your old card or any card for that matter. I hope this helps!!!