I got this for 70CAD(~55USD) And It seems to work, I've barely tested it tho, and don't have any precision parts or sources to test on. I have a Brymen 869 and MS5308 LR meter to compare against. I have lots ebay 1% blue resistors
The only precision resistors and temperature calibrated references/etc/ ? stuff I can think of having, would be in my tektronics scopes, and the BM869, BM235, and maybe in a cheap Vici VC99 DMM.
I have scrapped wifi modems, I have motherboards, don't if they could help.
I have LM431B 0.5%, TL431 1%, LM336z 1% voltage references. I have a few computer PSU's
I took it apart and some voltages I checked where great. It's a work of art in inside. Too bad the case and screen are dinged up, the LCD is nice and bright tho.