A used ispring RCC7AK reverse osmosis under counter water filter. Includes tank, tubing, various fittings, and new spout. This filter system is highly rated and is about $300 new. For more information go to ispring website. It is due for new filters.
A full set of 7 filters runs about a $110.
4 of them I changed every 3yrs and the 3 larger filters I changed yearly and that worked good for our water in Bismarck.