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 !!!

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
Add image file

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.