I probably have no idea what I'm talking about because I don't work in this space, but in a previous life, our company was looking at Nordic for chips, and they had some pretty solid offerings for bluetooth chips. IIRC it was around $5 per chip but I may be totally wrong. It was one of these I think, and it's been about 3 years since I looked into this https://www.nordicsemi.com/Products/Low-power-short-range-wi...