I bought a 6 stage RO from eBay, 100 GPD for $100. I use it for my fridge ice cubes too! Don't bother with the dual output. It sucks. The unit is slow.
My tap water was 500 PPM to start, this unit brings the PPM down to 110. I may add another DI filter to bring it down to 0 PPM. A 7 stage would...