add price to text option box

I am looking for an extension which will allow me to add a price to the options called "text". My current site (not opencart) allows me to have a text field option in which I can determine a price if customer wants to add a personalized name to their apparel. Currently with the option "size" I can add a price when adding a size to the apparel. I would like similar option for text field pricing... any ideas? I am using the most current version of OpenCart 2.X

example of how I need it to work: http://spiritcorner.com/store/WsDefault.asp?One=3300
site where I need to get this to work: www.thespiritcorner.com

JohnniZ120