Looking to get tunes back! Bluetooth or wired or whatever.

What I am looking for maybe doesn't exist. But wondered maybe my google skills just can't locate what I think I want.

Radio is dead in my 69, replacing with a "custom" unit that cost $100's is not worth it for me, I would rather spend that on mechanical upgrades etc. But it would be nice not to haul around a "brick" bluetooth speaker on the floor. Especially since I don't lock the doors since sometime the key has trouble unlocking it.

I have a single speaker in the dash. What I would like is a simple replacement speaker that either had a bluetooth built in so I could stream, or a simple headphone 3.5 mm plug. I would think that is a simple thing that might cost less than $100? Is there anything on the market like that? No volume control etc? Everything is controlled by the phone or device? Add a power line to the speaker, mount it in the original hole and kapow you have tunes!