What is a good price for Oticon Opn hearing aids?

I think that is a reasonable price for a pair, you could shop around and maybe get them for £400-700 cheaper. Obviously price is an issue for everyone but also very important is to make sure you go with a a clinic you trust and who will give you a great fiting anf service. The key thing to hearing well with a new hearing aid is having a clinic that takes the time to work with you to fine-tune the aids to your personal hearing loss and "how you hear". So, you may be able to get them cheaper elsewhere but make sure you don't go cheap and then sacrifice on the service.

The price you pay for a hearing aid will include the clinc's time for fitting and you should go back to them several times (at least) after you are wearing them to get them fine-tuned to what you want, that's what you are paying for, not just the aids themsevles.