If you want something cheap and effective the Bluetooth FM Transmitters do a great job. The just broadcast whatever they receive via bluetooth to a selectable FM frequency of your choice.
I bought one for Dad 3 or 4 years ago and he cant live without it. Apart from using it as a handsfree phone device he plays his internet radio through it morning and evening.
This is not specifically the one I got for Dad, but looks exactly the same.
https://www.ebay.com.au/itm/403071128169
It functions as a handsfree very well. Microphone quality is about the same as the old Nokia kits I used to have. Sound reproduction is pretty good too.
Although they can be a little hit and miss. I got one that looks almost the same as Dads and while it still does a great job the sound reproduction isn't as good. Is a little bit tinny. But it only cost me $14 so no worry, I'll replace it with something better at some stage.
Jump on ebay and search for "fm bluetooth transmitter" and you'll get a ton of responses and different styles for between $10 and $25.
If you want something quicker locally, Jaycar and places like that sell them. But expect to pay $40 to $50 mark.