Coast2Coast Music has a pair of Microphones for sale at a decent price. I might buy these when I get my tax refund.
Shaker Retro Rocket Harmonica Microphone. (about $120) This is a small mic and I think it would fit nicely in your hand and help to control the sound very well. Shaker mics have always had a good sound.

And this very pretty one
Bushman Torpedo Harmonica Microphone. (about $100) This is more like a vocal mic in a retro package. You would have to use a transformer to plug it into a tube amp, but it’s perfect if you plug directly into the PA.