I don't think there's a great deal of need for a setup on a UBass beyond what the factory does. I have a Kala spruce-top UBass, and I suppose there could be differences with other brands or with the newer Aquila strings, but the strings are so stretchy anyway that intonation isn't an issue, and a buzzy fret is usually just caused by the finger placement or lack of pressure. At least I wouldn't worry about buying one from a seller that doesn't set them up.
Even the wood choice isn't all that much of an issue; I went back and forth between the solid mahogany model and the spruce, but finally reasoned it wasn't going to make any real difference other than cost and appearance, and I think the spruce top looks fine. The unamplified volume is so low that who's going to worry about minor differences in tone, if you can hear them at all (I doubt it), and amplified sound should be the same. Plus, solid wood needs more care and pampering, so I reasoned that a solid-wood body was unimportant (though the spruce model has a solid top, laminate sides).
They're a lot of fun, and very similar to an acoustic bass in sound; combined with a battery powered amp like the Roland Cube, they are still very portable.