I dont really have any solid info on what to get, there are alot of R.O. systems out there. Interested in that as well, as I've borrowed my friends system. Puts out around 12 gallons a day.. Eventually I will need my own, so please share what you come up with.
I am not totally sure about this, but I think I've heard something about, you should get a system without water softener, because of the sodium that gets in the water?? Better read up on this..
Also I know, some systems you can set up with a float-shut-off valve, so it keeps your top-up\spare res filled and turns on\off the R.O. System as needed.