I agree with Ulsterman, your in-depth knowledge is amazing. I have done my own research after what you have said and I came across this link.
Cutting a long story short the 'All Wales Medicines Strategy Group' did an appraisal comparing Invicorp to caverject, including their own clinical trial. They came to the conclusion that Invicorp was equal in cost but had less occurrence of painful side effects that caverject and recommended invicorp as a treatment for ED in men where traditional treatments had failed. Then in July they overrode this recommendation with the following:-
"Aviptadil/phentolamine (Invicorp®) is not recommended for use within NHS Wales for the symptomatic treatment of erectile dysfunction in adult males due to neurogenic, vasculogenic, psychogenic, or mixed aetiology. The clinical and cost-effectiveness data presented in the submission were insufficient for AWMSG to recommend its use."
Also interesting was the following on an appraisal by the Doncaster Clinical Commissioning Group:-
"Acquisition costs – whilst the basic acquisition cost of this preparation is similar to that of alprostadil injection there is a further unseen cost to the NHS. The unusual distribution of Invicorp, from the manufacturer, is via a non-standard mechanism leading to Community Pharmacy potentially obtaining it via a route that excludes the usual wholesaler processes. This can lead to an additional carriage charge being passed on to Community Pharmacy, which can then be reclaimed. This on-cost charge is not charged directly to the primary care prescribing budget but is however paid for by the NHS."
All this of course is what you are telling us Lyn, so I should just listen to you and not bother researching :-)
I will take both of your advice I think and book an appointment with another Doctor and see if they are happy to prescribe it me via pharmacy2u rather than the regular route.