Do you have to pay somebody to plug/patch it, or do you have the tools to do your own? If you have to pay somebody to do it, I'd just get a new tire. Tires are often cheaper than labor.
I'd do your own, and use online vendors when local vendors want to charge $320 for a tire. Then I'd change the tire in the street, right in front of the vendor that quoted me $320 for 1 freaking tire.
Is their tire made of recycled condoms from Wilt Chamberlain's hotel rooms, and installed by tire technicians anointed by the pope himself?