Look on the left rear dropout for the serial. If there's also a small symbol that looks like a baseball, it was made in Japan, which is good. If the serial is under the bottom bracket and starts w an F=that means made in Taiwan. Which is less desirable.
Also that bike wouldn't have come w a...
Check the weight limits. Most minis have rider weight limits.
And, generally, minis are not worth quite as much as regular 20 inchers, since us adults can't ride em with out bending them all up. :wink: