Why would it be bad for that price? Highly accurate ADCs are pretty easy to make, provided you don't need a high sample rate, thanks to the magic of signal processing. Delta-sigma ADCs, and ramp ADCs can use a single bit of digital input + some pattern hold circuitry to do incredibly accurate measurements, it's just they take some time.
If you want a flash ADC that can do 16 bit (and can do 16 bit at 100Mhz), however you'll have to probably mortgage your house.
If you want a flash ADC that can do 16 bit (and can do 16 bit at 100Mhz), however you'll have to probably mortgage your house.