You can buy an "economy" set of NIST traceable gage blocks for about $120[1], that are accurate to 50 millionth's of an inch. Metric sets are also available in the same price range.
Fluke has an entire line of NIST traceable tools[2]
For a stiff fee, you can ship things to NIST to have them calibrated[3], or buy standard samples.
In the US, NIST traceable calibration can be had for almost anything. I suspect the same is true (calibration back to a national standard) in most of the world.
You can get GPS disciplined clocks for about $200, the long term stability of those are tied to UTC, which is as good as it gets.
If you can afford to spend more, there are devices that can input a laser, and tell you the frequency of that light, down to 1 Hz resolution. They use optical combs, and a lot of physics, and have an internal atomic clock reference.
---
My point is that we have an amazingly affordable web of precision that we can fall back on, this allows people spread across the globe to build interchangeable parts that will fit properly on a regular basis. It is freaking amazing.
