Any pump is better than no pump. The Osbon and the Soma are the Rolls Royce of pumps, but a Ford Escort Pump will get you there warm, dry, quicker than walking just like a Rolls, maybe not so luxuriously.
Forget brand names. Think about the task in hand, getting blood flowing to the regions I heard some months ago about someone else who could not get a pump on the NHS, improvised with a Hoover. Same principle applies. Put the bits in a tube. Create a vacuum. The bits seek to fill the vacuum.
And on the meantime,e there are pretty of exercise that you can do without kit to help your rehab.
What ever you do, don't give up on the playing and the manipulation. If you are going to have any success then early days stimulation is important.