Pressure sensors can be had of course. Not sure what you have in mind when you state inexpensive, but you can find items at Digi-Key here: https://www.digikey.com/products/en?FV=ffec5663
Here’s an interesting one: https://www.digikey.com/products/en?vendor=0&keywords=NSCDANN150PGUNV
Another thought is a pressure tank. These are also commonly available and can probably be sourced locally. Several options here: https://www.homedepot.com/b/Plumbing-Pumps-Well-Pumps-Systems-Pressure-Tanks/N-5yc1vZbqld/Ntk-Extended/Ntt-water+pressure+tank?Ntx=mode+matchpartialmax&NCNI-5
Mike