Filtration is a complicated topic.   My experiece is that it is complicated by those who want to sell replacement cartridges to ensure a continual income.  I do not support that philosophy – I want people to use less product and therefore have a lower consumer footprint.  I also support people being able to purchase direct and always provide the direct link to the suppliers.  That said If folks want me to do the legwork, I charge cost+ 10%.    Following is my recommendations for a potable water filtration system.
Recommend 100 micron flushable strainers  – Judo Profi Manual Backwash
Potable (NSF61 certified)
Pre-strain 30 microns (various suppliers)
10 micron bag filter (re-useable)  – Pentek
5 micron bag or 5 micron ceramic  – Pentek or Doulton
0.5 micron Sterasyl ceramic (Doulton) 0r a 1 micron (Doulton) coupled with either UV or chemical system

With chlorine injection I recommend a GAC Carbon and a KDF 55 filter to remove some of the chlorine and chloramine after treatment.

Filtration systems for the average house cost between $3000 and $6000 depending on your level of comfort.