Put two backslashes in front of dollar signs. For example:
Some prices: \\$3.10, \\$4.25, \\$8.50.
(running Jupyter notebook server 5.7.0)
You can escape $ with math mode by using a backslash. Try $\$$
$
$\$$
If you use <span>$</span>, MathJax won't process it as a delimiter. You should be able to enter that in Markdown. For example, I've used that here: $ This is not math $.
<span>$</span>