I think you can make a cheap-o pump for less than $50 if you are looking to get started. It is what I did for my first pump, many years ago.
Just go to any auto parts store and get a brake fluid pump (it has a pressure gauge built in) for around $30. Then go to a hardware store and get a tube of some kind of caulk and some plastic tubing to connect the pump to the caulk container. Then get a bike inner tube.
When you get home, cut the tip of the caulk container and squeeze out all the caulk. Take a long skinny something (like a chopstick or pencil) and push the top of the container (the part the caulk gun pushes down towards the tip) out of the empty tube. (Alternatively, you can just drill a hole in that piece from the tip if you let it dry first). Wipe out any residual caulk with a paper towel and the pencil/ chopstick. Let it dry overnight.
The next day, cut a length of inner tube about three inches long. Wash it out with soap and water. Stretch it over the end of the caulk container, half on the end of the tube. This is your seal. Cut a length of tube, attach it to the application tip of the caulk container and the end of the pump.
Take some lube and get it on your dick, and put it on thick near the base. You can use petroleum jelly, hand lotion or whatever you find works best for you. Spread a little in the inner tube. Pump your semi-erect dick into the tube and you are off to the races. A warm wrap around it is a recommended option.
You can take this into the shower or bath with you or do it out of the water.
Total cost is less than $50, and the size is a good starter for most people, around 8ish by 6ish. You can find clear or opaque tubes, but try to find one with no seams but that is made from one piece, to help reduce the possibility of a small air leak.
Added bonus: when you decide pumping is now a part of your long term PE plan, you can order a larger (and definitely more comfortable) tube from Boston Pump, or whoever, and you already have the pump, which is yours forever and useful with every tube you make or buy from now until you’re done with PE.
I can promise you cheap shit in PE is still overpriced, as it is poorly made and generally disappointing in function. Better to start this way if you want to save a few bucks, figure a few things out, and then ramp up in cost and quality.