Dupla CO2 Equipment Advice

Hi,

I am fairly new to the planted aquarium game. I have the right lighting and right substrate and my plants (HC, dwarf hair grais, Cypress Helferi, etc.) are all looking good. But it is time to get a CO2 system.

I want to get a complete system at a reasonable price. Ebay / craigslist have always treated me well in the past. So I am looking there first. I would greatly appreciate any advice / words of warning from the pro's.

I have found a used Dupla CO2 regulator (Amatur Delta) with magnetic (solenoid) valve, glass diffuser / bubble counter, and CO2 indicator.

It looks like all I'll need to find are a tank and check valve.

So my questions:
1) Any general advice about picking up a used CO2 regulator? (These things are designed to last and should be in good shape barring any abuse, no?)
2) Any word regarding the Dupla Amatur regulator? The CO2 regulator only has 1 gauge. Is the second tank press gauge necessary? Do the Dupla regulators have a needle valve to manage CO2 at small flows? (Is this something else I need?)


As I am sure many of you have experienced in the past, entering the CO2 game can be overwhelming. Specific or general advice is greatly appreciated.