i've got a spectrapure that works great, the typhoon is somewhat cheaper. either will work fine.
I would also get a ro/di unit not just a ro unit.
as for gpd, most people get BRUTE garbage cans and have the water drip into it all day. I do this and i turn it off, i'm in the same stage as you. I've got a 24gal and i've got a 75gal coming in two weeks.