a lot of hobbyists bought the Parker Hannifin H3L high precision metering valve and the burkert 2822 low power consumption stainless steel solenoid valve, and I think it is a good idea to reveal the cost detail so anyone in the process or want to build a set, can spend wisely.
here is the cost detail of below system. you will have good idea how much you need to spend to build such system yourself, but please don't make it a standard because your ability to find parts, parts cost, the risk of getting defective parts, the material to build, and the TOOLS, .... all are part of actual/final cost.
actual raw material cost:
Regulator, Parker Hannifin M2, $40, shipping $15
CGA 320 nipple and nut, $5, shipping/handling $3.
solenoid, numatic 1.5 watt stainless steel, $18, shipping/handling about $3 each solenoid
manifold, $5, shipping handling about $2 for each manifold
24V DC power adapter for the solenoid, about $5
Parker Hannifin H3L metering valve, $25, shipping/handling $3
JBJ bubble counter, $12
pipe fittings, washers, terminal connectors, teflon tape, loctite threadlock sealant,.. about $10
Total is around $146, (add all numbers together from above)
The used double stage regulators we can get are all $500-$1000+ in retail as new, but we actually pay for only about 1/10 of that new retail, so EXPECT risk of getting defective units(because they are cheap used)!
From personal experience, after a series of different steps of testing that runs up to two weeks, the failed/defective units are about 30%, the remaining 70% are full functional units.
mainly tools. bench vise, torque wrench, drill, tap, ... all kind of wired stuff and expenses for the purpose of the build. Can be really expensive! personal experience
cost nothing if you build the system for yourself, but how many hours spent, could be calculated: the hours it took you to learn, to find/buy parts, and finally to put the parts together.