This is quite a complex scripting task. Is the price always going to be inside of parentheses? Will it always have the dollar symbol before it?
If not, how do you suggest differentiating between the item number and the price? I suggest you look for a different way of getting this information.
If one sets the format for the fields to sum to "Number" and selects the Currency Symbol to use, then any of the 3 calculation options can perform the task.
The display format is independent from the actual value of the field.
There were typos on my part in my post. An item may or may not have a price with it but if it does it will follow that format with the parentheses and with the dollar sign. There could be other numbers in the text field that aren't cost. and the user of the form can freely edit the text. Essentially no dollar sign preceding, than it's not a number to include in the total.