Create the following file structure to avoid making any changes to the Magento Core files.
Then open and and copy the content from app/code/core/Mage/Catalog/Block/Product/View/Options/Abstract.php into the Abstract.php file you just created in your local folder.
In your new Abstract.php file run a search for $sign = ‘+’; (It’s in the _formatPrice function if your search doesn’t work)
Replace the ‘+’ with ‘ ‘.
Save, Upload, Enjoy!