I'm interested in gettin a hot water on demand tankless thing. Anyone have any recommendations? Propane fired & no electricity is what I'm after. And, oh yeah, inexpensive. Is that possible? The Rinnai systems that I see at the shops are to spendy for us at time. I've seen some cheapos that say like 2 gpm- I'm not even sure what that means. I know what it MEANS, but the reality in action is the part I'm inexperienced at.