Have a hard to mic string instrument, but dont want to install a fixed pickup? Myers makes this stick on mic that can fit just about any instrument. It has a suction type of cup to attach to the instrument and a flexible goose neck arm with the mic at the end. The body of the unit has a preamp. It is highly regarded for its sound quality. I am not really playing out with the instruments I bought this for, so time to sell it. Here is the page from Myers with info about it, scroll down to the section for The Grip 3 inch Gooseneck: https://www.myerspickups.com/pickups/the-grip-series.
And yes, you accordion players will want to consider this one too! 95 cash