in that case, u have to avoid bacfree as they are in the >3k region. u also have to avoid those with auto-backwash feature, since that would be more expensive

lots of brands out there, it depends on what ur expectations on the performance of the filtration. personally for me, is just to have clean water to use around the house (bath, wash clothes, etc), not until the point that its drinkable.

what u have to consider is the cost of the consumables (filter sand, elements, how often to change) and warranty, especially on the "switch". usually there are 2 warranties, one for the filter tank, another for the switch. so u have to check on that as well.

don't forget labour cost as well for installation, as you may need some pipes for that..