Kokomo,
You CAN do this in the price range your looking, all depends on what you decide to use as a dish.
There are many options out there.
You say you want one that goes on top of the RV, you'll have to consider where you park the RV if thats the case as Line of Sight is critical.
Like mentioned above Winegard and MotoSat do them, I think KVH does as well.
For the ones on the RV, expect to pay $1400 on the low end.
Some have the reflector exposed others are a dome so there's nothing exposed.
When you start looking, make SURE that it handles the DIRECTV HD, lots of them handle HD, but they use a different sat for the HD, Directv uses the 99 and 103 for the HD programming, most HD set set up don't handle them.
I was recently looking at Camping World and they claimed to have the "Traveler" that handles D*, but I don't remember what was involved in it.
I think this is the same one here :
SK-3005 TRAVELER RV DirecTV Slimline LNB SATELLITE TV ANTENNA
$1699 is Members price at Camping world
http://www.campingworld.com/shoppin...imline-ka-ku-multi-satellite-tv-antenna/37343
IF your going to get the HD DVR, make sure you have 2 runs of coax to the recvrs, I'm pretty sure the ones shown are not the Single Line set ups.