Reverse Osmosis System

I am moving to a new home where the current owner will take his RO system with him when he moved out. I wanted to put one. I've seen some old post on RFD.

Just wondering if someone have suggestion on where to get plus installation but not too expensive.
I have seen rentals like reliance and they are expensive like hell.

My friend knows someone who sells Culligan brand. The guy is charging me close to 1.6K including installation.

I know some have also suggested to get it on Amazon.

However, does anyone here have any suggestions? Thank you very much!