You can get an Everpure system that filters, softens and improves taste for about $100
Add $20.00 for 1/2" braided hose from Bunnings and one 3/8" to 1/2" BSB male fittings; one 3/8" to 3/8" male fitting. Might need a 3.5bar pressure reducer - $35.00 - $65.00 and a T if you use cold water mains supplied to your sink faucet/mixer.
So - $200.00 maybe?
Any resin system will increase the longevity of your machine. I just refurbished a MegaCrem Compact and scale had completely plugged the hot water tap at the boiler fitting (low on the end of the boiler).
Whatever system you use change often and do a water hardness test if possible before so you have an idea how aggressively you need to combat mineral precipitation.