This is where I literally just ordered them from yesterday, but now it's not saying out of stock:
https://www.aliexpress.com/item/Latest-KZ-Bluetooth-Earphone-KZ-HDSE-Bluetooth-4-1-Headset-Hifi-Wireless-Headphone-APTX-Lossless-Music/32753479112.html
I searched and was able to find them on Amazon:
https://www.amazon.com/HDSEBluetooth-Earphone-Bluetooth-Wireless-Headphone/dp/B01KSRCE1M
The sad thing is when they were selling on Gearbest, they were like $12 shipped (vs $30 on that Amazon link). I wish I ordered them from Gearbest when they were 1st available :0(
You might be able to find them on one of the other many Chinese eshopping websites (banggood, dx, fasttech, tmart, geekbuying, dealextreme, taobao, etc).
Just search for 'KZ HDSE bluetooth'
BTW, if you want to read the product description as well as customer reviews, check these 2 links (even though not for sale at either link, the reviews look very promising):
http://www.gearbest.com/sports-fitness-headphones/pp_469338.html
http://www.banggood.com/KZ-HDSE-Bluetooth-Headphone-Sports-Earphone-p-1082324.html
Another option to consider might be something like this:
https://www.aliexpress.com/item/2017-newest-Wireless-Bluetooth-4-1-Cable-HIFI-Earphone-MMCX-Cable-Support-Apt-X-Aptx-bt/32792604370.html
If you already own an IEM you like the sound of that has removable MMCX cable, you just swap the wired cable with this bluetooth one. And if not, there's lots of really good sounding yet value-priced ChiFi models that have MMCX. This would give you the best of both worlds.