Per above. Have a Bell Bulliit helmet, looking for a recommendation on microphone/speakers that can be retrofitted. Ideally at the cheaper end of the spectrum

What is it you are looking to do with it? I know that sounds like a stupid question but it does make a difference.

If I was wanting to listen to music on a long ride, I find my moulded Ultimate Ear headphones far, far better than any bluetooth speaker system in the helmet. To be honest, they’re about the same price.

Rachel

Scala Rider G9/G9X are good – that’s what I use for phone/satnav & bike2bike comms.

Bit of a faff to learn at first but pretty good once you get the hang of them

I use Scala Packtalk for rider to pillion, rider to rider along with sat nav and phone/music by Bluetooth. I also use them with custom earplugs with built in speakers and filters instead of the speakers that come with the Bluetooth system. If I’m riding in my own and not needing sat nav I just plug them into my phone.
As Rachel said what do you want from them?