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.
All putting greens should be laid on a hardcore compacted base. Granite MOT type 1 standard is the best choice. On top of this compacted sharp/grit sand or even best granite dust.