How can I tell a good cello from a not so good cello?

My daughter has been playing for a couple years using a school instrument. Her teacher says that she’s playing above the level of the instrument (I interpret that as meaning the instrument is holding back her progress). So if we buy her a second-hand cello, how do we know we’re getting a good one? There are so many makes and models, many of which I can’t even find information about in a Google search. I don’t want to spend good money on a piece of junk. Thank you in advance.