I think the ones more commonly used in the UK are Stockholm3 and Proclarix. I think these are around £300, and as a private patient you would probably find you also have to buy consultation which might add another £100.
Graham Fullford Charitable Trust has for very many years been including Free PSA tests when the Total PSA test result is between 2 and 10 (originally 3 and 10), and using their large database of tests, they've found this much more specific for significant prostate cancers than just using PSA alone.
They may have an option to do Stockholm3 or Proclarix in similar circumstances now (it was being talked about).