Grigg,
I have tried them all. Here's what my experience was:
Cialis 5mg nightly - started on it, was moderately effective. about 70% firmness but not enough for intercourse. Stopped it due to an alergic reaction after about 1 month.
Viagra - Bing, up and solid, fun can be had. Get the headache and stuffy sinuses.
Levitra - Up and solid as well. Get a milder version of the headache and stuffy sinuses, and does not last as long as Viagra
Sildenafil (Viagra generic) - Works the same as Viagra
What works and the SE's you get is unique for each guy. I am only 4 months post RP, so I'm still in the healing phase for the nerves. Your mileage definately will vary
My surgeon has a pharmacy in Canada that he has had great success with for the generic. His practice will call in the prescription to this place only. I know of this one and one other that is likely the one Jazzman referenced you too. E-mail me and I'll send you info.