Chris I'm not advertising a company. I have installed for various companies. Something like this through one of the leading firms would probably cost £3000-£4000. The best way to keep them clean is using a leaf blower sucker to clear the debri and every now and then brush them.
Out of interest I take it you have made it with a couple of breaks? A friend of my dads used to have a full 18 hole putting green in his garden and hosted a yearly competition to raise money for charity. Easily got a turnout of over 100 people