Have your torque wrench checked for accuracy. The possible part numbers for the oil check valve bolts are: 1570342010 ; 1140149575 ; 1570366010. I think the price you are being quoted is a ripoff. They normally sell from between 10 to 13 USD each when they can be found. Here is a link to OEMparter with a list of dealers that may have it.
http://oemparter.com/oem-parts/1570366010.html
I have 6 brand-new ones that I could throw up on eBay if that helps you.
Bru