I dropped $120 on a Starrett combo square about 2 years ago. I also have a set of made-in-India machinist squares and one Woodpecker square. I've tested the all of them for squareness, and they are all quite good. But I've never, not once, regretted buying that Starrett. Even though my eyes can't see any difference in accuracy between it and the others. I don't really know why - I don't believe I need aircraft industry accuracy for woodworking. But I trust that Starrett as my best measuring tool.
"All that is necessary for the triumph of evil is that good men do nothing."
“If you want to know what a man's like, take a good look at how he treats his inferiors, not his equals.”