Like with EE.SE, it seems like using the default
$ to signal for MathJax rendering is not the best. If I say it maybe costs $30 to do this one thing or $50 for another, my post or comment could wind up mangled.
I really don't get why
\$ isn't the default for SE sites. For those that are extremely equation heavy (Math.SE/MO/Physics.SE), sure, change it up, but everywhere else it's often surprising and unexpected.