I have seen new Stenner pumps on eBay for $180. It just depends when you look. The classic fixed head series is all you need (45 or 85 series). Variable head works too, but most people will just set to maximum and control the Stenner with a timer. Any pressure rating is OK since most pools have 10 PSI or less at the point of injection. The Stenner Econ T will work too.
Stenners Single Head Fixed Output Injection Pump
Stenners Econ T Series is a programmable pump for timed applications.
This particular link is one of the better prices I have seen for a turnkey setup. Stenner 30 Gallon Tank System With 100 PSI Fixed Pump 1/4 Inch Tube
Just be sure that order the pump with correct voltage (usually 120V for most people).
If you find a deal on one that pumps too much for your needs, you can just change the pump tube to get a lower output.
Stenners Single Head Fixed Output Injection Pump
Stenners Econ T Series is a programmable pump for timed applications.
This particular link is one of the better prices I have seen for a turnkey setup. Stenner 30 Gallon Tank System With 100 PSI Fixed Pump 1/4 Inch Tube
Just be sure that order the pump with correct voltage (usually 120V for most people).
If you find a deal on one that pumps too much for your needs, you can just change the pump tube to get a lower output.