I just picked up a really clean 850 for $70 on ebay. Some of the ones there are old and not in very good condition. But keep looking and you might find a good, relatively new, clean one for not much money.

I still like my 850s because they have 10 LEDs buttons, rather than the more common 6 in most newer models.

That said, a 780 is a decent entry level remote. The programming is a little different, but if you know the 850 software doing a 780 with CCP is pretty straightforward. Just make sure you get the software with the remote.