Don't give up on the P7. If you keep looking you will find one in your price range. You will most likely be looking at a police trade in, but who knows you may find a new one. I bought mine new in box for $750 about three years ago. I passed on a refurb for $600 a year and a half ago. You probably won't find a good deal on Gunsamerica or on any H&K boards. You are looking for someone that wants to sell their pistol and either doesn't mind putting a low price on it, or doesn't know what the max is that they can get for their gun. Or they don't care.
By the way, what is a conventional pistol action. Would that be single action only with safety, single action only with safety and decocker, single action only no safety, double action only, double action/single action with decocker or double action/single action with safety and decocker? Have I missed any? Probably. Anyway, every pistol has a manual of arms. If you have never picked up a pistol, why would the P7 be any harder to learn than some other manual of arms. To me it is the second most simple. The first being a double action revolver or a double action only semi-auto. Those are point, pull trigger. The P7 is point squeeze, pull trigger. I think the P7 is easier to learn than most semi autos. One control drops the slide and functions as the safety, instead of two. And the trigger pull is consistent from shot to shot.