I have a lot more in it than necessary as I jumped the gun and ordered the wrong fittings the first time around and would purchase a few other things differently. Plus I had to pay relatively expensive shipping multiple times. It could also be built less expensively if only used as a dead head device. But I wanted to build one that could be used as dead head or operational pass through, to cover all bases. And also the reason I ordered couplings for all types on my tractor.
The only design change I would make is to use a gauge with a back mount fitting instead of the bottom mount. This would allow use of a 90 degree swivel that seems to swivel independently in place when installed. I am currently using a straight swivel from Northern Tool who's position can only be adjusted by loosening the fitting- moving the swivel and then re-tightening.
Pricing listed below is what I could build another one for with my new found experience level. Most of the items came from Discount Hydraulic hose, except the hoses which were from Amazon.
Basic pricing now I have built one and know what fittings to use:
36" Abbott 1/4" 5800 PSI hose: $17.10 (4000 PSI versions are less expensive at many places)
Bottom mount 5000 PSI gauge: liquid filled: $17.31
3/8" T fitting: $7.90
Each pair of ISO hydraulic couplings: ~$17 - $20 (ISO 16028 coupling pairs are more like $75)
Swivel fitting: $13.30
Misc. fittings, adapters, etc: $35 - $50
Shipping: $15.00+