Hi, probably the reason why you have had no answer is because there are so many variations in systems all geared for different requirements.
It depends on how much water you need per day, what is the TDS of your tap water, do you want a home based system or a van system or trolly system..........
Work out your needs and then look at only the systems that fit.
Or if you want to build your own system then look at web sites that supply both full systems or self build.
Try gardinerpolesystems.co.uk or gapswater.co.uk or ro-man.com to get an idea of prices and whats available.
Good luck