I would go with one of the RC sponsors that specialize in water treatment, I use the filter guys myself. I would suggest a RO/DI unit with a Dow filmtec RO membrane and a vertically mounted DI filter housing. You can expect to spend $175 - $300+ with some units going over 1k. Then as an upgrade some filters have either built in TDS meters (good for quick reference testing water before and after DI filter) or handheld TDS meters, water pressure gauges, float switches, booster pumps, and Auto shut-off valves so you don't have to baby sit the on/off water supply. Some units are much more efficient then other and may be worth the extra price tag. Depending on the quality of your water a water softener may not be a bad idea.
This is an interesting article regarding Chloramine and how Carbon, RO and DI is used to effectively filter Chloramine.
http://www.reefkeeping.com/issues/2003-11/rhf/feature/index.php
When choosing a water filter, It depends on the quality of the water going into the filter. For instance If you live in an area that Never treats the water with Chloramine and the TDS is not thru the roof then you may find that a good Carbon/RO filters works for you just fine. If your local water treatment facility uses Chloramine, TDS is high, or you live in an area that may have lots of run off from the farming industry during certain times of the year then Carbon/RO/DI is likely the best filter for you.
This is the unit that I'm using and it's moderately priced. The filter guys are gr8 to work with and I highly recommend them.
www.thefilterguys.biz