The Whedon model at $11.99 looks very much like one that the local utility company gave everyone for free about 30 years ago. I still use it every day (in my stick house). When I change abodes, it goes with me.
They make a model called X-Stream that claims to convert weak water pressure psi into high pressure with no extra water use and nothing more than the showerhead. You can find it at rv accessories for under $20.
Oxygenics. Sprays really hard. It will get the shampoo out of your hair. I don't like the twisty turn off valve on the bottom of the Oxygenics head, hard to twist when your hands are soapy. I took the valve off and screwed the hose directly to the shower head (had to double washer). Installed a $5 valve from Home Depot on the water faucet where the hose attaches in the shower. The shower head is pretty heavy, so we lay the head on the shower floor while we travel.
For a really nice shower with a steady stream of water, install an expansion tank after the water pump. However, installing the expansion tank might lead to longer enjoyable showers, using up your water faster than you wanted.