The ampersand-pound sequence is the correct HTML code for the dollar sign, and well behaved email clients that interpret HTML should display it correctly (which is why the code is converted to a dollar sign on this forum). So for HTML format emails I think that the code is correct. If you are looking at HTML format emails, could this be a problem with your email client?
HTML format emails include a text only version as well. It does look as though there is a problem here. The HTML dollar code is still present so this could be your problem, if you are looking at text only format emails. My EMail Client (Thunderbird) still shows this correctly even in text format mode, but I have found at least one other email client that shows the problem you have described.
I sort out a fix, and put it in the next release.