Help making a portable speaker

Yup, drivers buzz if they're not symmetrical or not weight-balanced or if there is too much tolerance on the magnetic assemblies.

I forgot to check for drivers tbh, I'm going to do that now and will post link in a few.

example of a 60mm driver:

http://www.conrad.de/ce/de/product/303672/Visaton-FR-8-Breitbandlautsprecher-8-/?ref=category&rt=category&rb=1

as you see, it's not expensive, but it's solidly built (240g weight, these will not rattle and buzz!). These are made to be independent of the cabinet structure, there is a complete datasheet available on them in case you would want to optimize, and they have a low resonant frequency, so a pretty good bass performance for the size (of course not subwoofer territory).