You didn't say if it was the high or low beam and you haven't filled out the "profile" area about yourself and car. We don't know where you are located (general area like mine is Massillon, Ohio) so we can't do a search in your area.
Generally the least expensive place is Ebay (compared to "used car parts" searches).
These are "aftermarket" (not KIA OEM) headlights. I bought two for my 98 Ford Contour and they were actually better than my old discolored OEMs.
High Beam headlights on Ebay are going for around $100 with shipping included for new replacements.