Jerry,
Dish has recently introduced Dish on the Go, You can purchase it by the month while you're on the road or you can add it to your stick house service for $7/mo. I added an external hard disk that becomes a dvr.
Check out:
http://www.dishformyrv.com/
The VIP211 receiver is $149 although I have seen them as low as $100 on ebay.
I don't have experience with DirectTV but the Dish package has worked well for us.
Ken