All nerves removed during Operation seven years ago. Any suggestions for Erection

I'm very fortunate to be alive after a bout of Gleason 8&9 Prostate Cancer in all 12 biopsy cores and extensive local spread in all directions including lymph nodes. Due to the seriousness of my cancer, all the nerves around the prostate were removed during surgery as expected plus 40 rounds of radiation and two years of hormone theropy. Since then, nothing has come back sex wise other than desire. Pumps don't work, Viagara does not work, and maybe nothing will, but if any of you have some low cost suggestions please post. Again, all the nerves were removed due to the aggressive nature of the cancer and if nothing can be done, that's fine; I'm alive with undetectable PSA levels seven years out!

Try “penile implant” in the search bar, there are a number of posts on HW.
Injections are the only other method I am aware of that might work that would be considered low cost.

Bob,
The two ED therapies that might work for you at this point are injections and a penile implant. A normal erection is caused when the erectile nerves stimulate the release of Nitric Oxide into the blood vessels in the penis. This causes the spongy erectile tissue to swell causing an erection. Without functioning erectile nerves no Nitric Oxide is released and there is no erection. When the release of Nitric Oxide into the penis ends the Nitric Oxide is gradually removed by an enzyme called Phosphodiesterase-5. In healthy young men the release of Nitric Oxide easily outpaces its removal by the enzyme. In older men it can be difficult to keep up and they tend to lose their erections if they are distracted. All of the various ED pills work by blocking the action of phosphodiesterase. None of the pills actually cause an erection they just help keep it from going away. Since your erectile nerves are gone then pills can't help you.
Injections work by injecting drugs into the erectile tissues that mimic the effect of Nitric Oxide, causing the same swelling of the tissues and an erection. Because the drugs don't require the action of the erectile nerves and the drugs are not eliminated by the enzyme they tend to work much more reliably for men who have lost erectile function due to prostate surgery. They also don't require sexual arousal to work. You can inject while doing your taxes and it will work fine.
The reason why injections sometimes fail to work satisfactorily is a venous leak. The veins in the penis are designed so that most of them get squashed flat when a man has an erection, trapping blood in the penis and preventing the Nitric Oxide from being washed away. Men who have a venous leak have veins that don't squash properly and this can cause drug-induced erections to be brief since the drugs are washed away by the blood flow. (The opposite problem is men whose veins squash too well; they are the ones who wind up with the 4-hour plus erections who wind up in the emergency room.)
The next step for men whose venous leak prevents injections from working satisfactorily is an inflatable penile implant. It consists of two flexible plastic cylinders that are surgically inserted into the erectile tissue (one on each side) that can be inflated using a squeezy-bulb pump installed in the scrotum. When a man wants an erection he locates the bulb, gives it ten to twenty quick squeezes and he is good to go. When he is done there is a button on the side of the squeezy-bulb that releases the pressure. After an initial period of getting used to the device (and getting past the problem that they tend to hurt the first few time you pump them up) they give a useful and fairly natural-feeling erection. I like mine well enough.
You probably will want to start with injections (talk to your urologist) since the tissues tend to shrink with disuse and the surgeon can only put in an implant that will fit. Injections should help you evaluate what you still have to work with after seven years and will help (a little bit) with getting things stretched back out. You may be happy with the results of injections (unless you have an excessive venous leak) and even if you eventually opt for an implant the stretching from the injections may get you an extra centimeter.
When you talk to your urologist about injections be sure to mention that you are interested in trimix. Trimix is a mixture of several drugs that work synergetically to produce an erection with fewer side effects that the single-drug options. Also, trimix is a compounded drug. You get it at your local compounding pharmacy where they mix it up for you. Trimix comes as a small vial that you keep in your refrigerator -- it's not cheap but since you can get anywhere from ten to thirty doses from each vial (depending how much you need each time) is it vastly cheaper that the brand-name injections.
Good luck. Let us know how things work out for you.

Bob,
If you opt for Trimix, pay attention to your "guy" for Peyronie's disease, which is curvature of the penis. I've seen online that over 15% of men using Trimix or Bimix develop Peyronie's. I don't know if that estimate is true, but it sure happened to me. The Trimix worked really well for me until the curving started. And I'm not talking just a mild curvature -- more like just about 360 degrees. It doesn't matter for me anymore because I'm on lifetime ADT, but for anyone in it for the long haul, pay close attention. At the first sign of misalignment I would make an appointment with your urologist.