Right now Tooldiscounter.net has the Milton 4-in-1 tire valve repair tool for $1.05.
The 4-in-1 tire valve tool is used to remove the valve stem of a tire valve, rethread both the inside and outside of the stem, and remove a broken valve. It’s a handy little tool that you only need when you need it, but if you need it, you need it! There are cheaper ones out there but the Milton seems to be higher quality. At least their catalog gives the tap size, if you’re curious: .2108″-36 tpi.
Milton 445 4 Way Tire Valve Tool [tooldiscounter.com]