Spectrapure UPLC II. I also own the Avast but can't recommend it at this time. They are working on correcting my issue though, so we'll see. I never had a problem with my Spectrapure and Jeremy's support is second to none. Neither Spectrapure or Avast are $100 or less.
It looks like avast ato is about 90.00 w/o pump or shipping right?
The ATO outlet, or controller interface (output) is $90 yes. You also need a peristaltic pump which is another $100 from them. You could go cheap on the pump for $50 instead.
Aqualifter pump works great for low head pressure
Coming in at $106 hard to beat. Also Tunze has a great reputation for making quality products.
http://www.marinedepot.com/Tunze_Os...f_Plug_In_Units-Tunze-TZ4114-FIDPETPU-vi.html