Just in case y'all haven't found a good solution.
The Bose Soundlink Mini II is about $150 at this time ( new ). Used are much cheaper and might be good quality.
Charges from a USB mini cord. Really easy to setup, charge, and grips the dash fairly well. I do plan to put a little silicon pad below it to protect the dash.
We like it for the music plus Waze navigation voice guidance is easier to understand than from our smartphone speakers. Supposedly can be used to answer, initiate phone calls but we don't use it for that.