from my point of view, having made only about 10 of these, the cheapest way to make a nice flipper is.....

£5 compressor. these get to anywhere between 100psi and 150psi before the pressure causes heat backup and the compressor cannot go any further with the pressure. it is in effect self regulating, crude, but it works.

to save more cost, trial and error at home with small diameter holes will limit pressure further, aim for 50psi to avoid the need for prds, although event organizers have been known to allow compressors without prds

pipe buffertank, a long coil of the pipe going to the ram acts as a buffertank, and is light, cheap and very effecive, as proven by whipper.

valve, a single acting valve is fine, easily picked up for £10, and will flow enough gas to make a nice flipper.

a cheap plastic ram from the £1 shop is a large diameter, long stroke solution, but having tested them dont go higher than 50psi. you have a ram alex, so no worries.

finally, bungee return, dont need an exhuaust valve if you have a leaky ram (like to £1 shop one) or drill a 1mm hole in the ram.

cheap, easy, and SAFE!!!

e-mail me for info, i have most of this in stock, and beware overly expensive advise. A lot of money is wasted in this sport following other people, when there are better/cheaper/simpler/safer ways of doing things.