Kinetico will be pricier. You have quite a few brands (ebay) that work on the same principle. The topic was already discussed but I can'tsearch as I am on my mobile and Tapatalk.
I have had one fitted, the difference is striking (Kent, very hard water too) and I will not hesitate to have another. It's cheap enough to maintain (salt, about 2 blocs per month for me but as I said water is really hard) but price wise you are in the right ball park.
Unless you have a hot water tank be prepared to accept a small drop in flow.