Hey! I'm on my phone at the moment, so I can't check for certain at the moment, but you're not the first one to bring this up - unless I'm mistaken I think I added a record in the localization that allows you to change this. I recommend taking a peek in there, I will look myself when I can as well.
Edit: Yes there is a record in the lang file that you can edit the symbol. For example if you want it to be a dollar sign change the following value from this:
["economics currency format"] = "{0:C}",
To this:
["economics currency format"] = "${0}",
Let me know if you run into any issues.