Quantity: 1bag=10pieces, Model: 191-212.
Aliexpress
I could not find it on Aliexpress. Click here to search by yourself.
Here are coupons that you can use.
Updated:
Banggood
Warehouse in China.
Link: Lead Free Sensor 191-212 for Tip Thermometer Soldering Iron
Price: $-3
It looks like this item is out of stock in Banggood. If you found it then please send me the link. I will replace it.
Click here to search on Banggood!
Additional Banggood coupons:
1. First page
2. Second page
Price history and price alert
Do you need price history chart (for all/most countries) for Lead Free Sensor 191-212 for Tip Thermometer Soldering Iron? There we go. The lowest price was: $3.6.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood and Aliexpress (only if product name will be the same as on Banggood and I will post it on social media though, so it’s more like Banggood price alert)).