The ribbon would be the cheapest option, however coming from experience that little ribbon is a real pain in the #@# to install and requires lots of patience. If you want you can just buy a totally new back assembly and that will have a new ribbon installed for your convenience, however this option does cost a little bit more.
Here is a link to the Ribbon
Here is a link to the Back assembly
Also if you are unfamiliar with the repair process here is the link to a back assembly replacement guide, [invalid guide link] is the link to the ribbon replacement guide. Please note that the link to the Back Assembly guide does link to a Battery replacement guide but it still shows you all of the principles involved in the replacement.
Hope this helps :)