What does your form field look like for this form?
Are you getting this error in server-side validation or from the browser?
To be clear, I’m talking about forms.CharField (or the TextInput widget, or type="text"), notmodels.CharField.
Again, your issue here is not with “trying to save the comma”. Your immediate problem is that “35,000” is not a valid type="number" input in your input field. You’re not even at the point where it’s trying to save this to the database.
Side note: I sincerely hope you’re not trying to use a FloatField for a monetary value. That’s a huge mistake, and the reason why Django (and databases) provide a DecimalField.