Its cheaper to get purefreedom system, as a pump costs £70-£80, flow controller £60-£70, 100 metres of microbore hose and metal reel will be about £150, 18ft pole £100, 250ltr tank £120-£150, DI vessel £30, plus mixed bed resin 25kg=£70-£80.
then you have all the fittings, rectus 21 tap fittings etc £20 for the tap.
then a deep cycle battery, atleast 65 amps per hour £40-£60