I see someone on Ebay is selling a bunch (more than 10) of these sensors shipped for $36.72 ea. May be a good opportunity to get a spare just in case. That's the cheapest I've ever seen them. Search "Bosch 17014".

 

That is a good price. I paid close to 60 for my spare. Amazon.com had them cheaper but won't ship to Canada for some reason.
Ron