What is the Best way for Finding Water Filters for Kitchen....?

First install, I'd go to Home Depot, and get something I could look at first.  They also have the ancilliary parts that might be needed, like a dual-output cold water valve, tubing, etc.  Once you figure out how everything works, you can go for best price on eBay or Amazon.  At least, that's what worked for us.

the ones from the local big box store are more than adequate ... and a lot cheaper then the fancy ones sold to you by pyramid schemes.

most of the bugger hardware stores have those filters 

filters.com. I saw a commercial for them.

Osmosis water filter is the best product for home kitchen.