[jQuery] Problem with eval()

Hi

I have an ecommerce site based in WordPress. Im having a small problem with the js.

Problem - When you have a number of items in the cart, and you click the change currency button, ( any of the options, pounds, dollars or euros)
the js returns an error when trying to update the prices in the cart. This happens in FireFox and IE8, but in FF it carries on running regardless of the error, IE8.

Site:http://www.celticrug.com/

I did some de bugging and this is where the error is occurring.
http://www.celticrug.com/wp-content/wp-e-commerce/js/wp-ecommerce.js
line 336 “eval(returndata);”

This is whats is being evaluated and outputted.

product_id = 8;
price = "$100";
numeric_price = "100";

This gives me a “Object does not support this method or property”

If anyone can give me some advice as to how to correct this it would be much appreciated.

PS i have tried removing the currency symbol that gets added in, it still bring back the error.