Unless you're on well water you don't need anything elaborate. Just buy a standard 2.5" x 9.75" water filter housing.
The housing looks like this and is Size 1:
http://www.purewaterproducts.com/standard-housings
The faucet looks like this:
http://www.purewaterproducts.com/ledge-faucets
This filter cartridge will filter out all the nastiness, including chloramines. It will last for 20,000 gallons.
http://www.purewaterproducts.com/products/fc020
I've been using a similar setup to this for years and it's been great.
You can buy the housing and faucet at any home improvement place, this is just the place I buy the filter media. The KDF85 media along with CATALYTIC carbon is the key to the purest water and long life.