Hearing aids

I've worn nhs AIDS for fifteen years. They are behind the ear but that doesn't worry me as my hair covers them. I have a good service from my local audiology dept and free batteries. I've noticed that my son is now hard of hearing. I know that he wouldn't wear obvious AIDS and am wondering if anyone has experience of the smaller ones I've seen advertised. .. And the price of course. I've heard that our nhs no longer prescribe new AIDS.