This model generally sells for between $100 and $150, so if you can grab it for $50, it's a steal. It is highly rated, and will have more power than you'll ever need to boil 5 gallons.
Since it has a built in regulator, you can control heat output (and thus propane consumption) by simply turning it down . . . remember, any time you see flames come out around the bottom of a pot, you're wasting heat. A lot of people just buy these things and put as much power on the pot as they can . . . but the truth is, you get the BEST heat transfer to the liquid when the flames are adjusted properly. Let me put it to you this way, you wouldn't put your smallest cooking pot on your biggest burner all the way on high . . . so don't do it with your brew kettle. Keep the flame properly adjusted, and you'll boil quicker without wasting propane.