Fuel Pressure Gauge - Which to buy ???

a 1990 Olds Silhouette 3.1L TBI
a 1994 Buick Regal 3.8L EFI
One has the TBI the other has a EFI. The good news is that I have
two different type of systems to learn on. The bad news is that I am completely clueless on equipment to test the fuel pressure and injectors on each type of system.
A little help is appreciated... what type of tester to get ?? Any suggested models ?? I can go for the medium quality as this is strictly DIY'r and seldom used.
Thanks in advance !!!
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