I can strongly recommend the new Dusty P20 Harp Pickups which produce a good, balanced, natural sound and can be used at much higher volume than any microphone without creating feedback. There have been many different harp pickups and microphones over the years, but I feel the Dusty P20 is a significant improvement on anything that has come before.
The P20 pickups can be fitted to new harps or to existing Norris harps of any age and the cost of a pickup is currently £298. Fitting takes about one and a half hours, so can be done at the workshop while you go and get a coffee ... and costs £45 ... so your total cost is £343.
For anyone playing professionally through any kind of amplification, from a small amp at a wedding to a monster PA system at a stadium gig, this is money well spent, as the ease of set-up and the improved sound quality is excellent.