Years and years ago, I bought an official postal scale from the USPS, believe it or not for $10.
Well, they are $35 now but they still sell them:
USPS® Digital USB Postal Scale, 25 lb. max. | USPS.com
And now they have USB connectivity I guess for Stamps.com or USPS priority shipping methods. I don't do any of that, I just order stamps online and mail first class, but I know my scale has performed perfectly all these years, so it was a very good investment for me. I know I've had it a good 15-20 years now.
I also bought (on Amazon) a scale calibration weight so that I could test check the scale occasionally and verify it is still working properly.
They also have postal scales on Amazon, not USPS official.