Tires??

my husband and I live in Essex Junction, and we got a flat tire last night. does anyone know where i can a) find an affordable replacement and b) find someone who will replace just one tire. i called walmart to see if they would, but they’re unwilling to replace a single tire. we have less than $200, so i can’t afford to change out three perfectly good tires just to fix one flat. does anybody have any suggestions? i can’t uber to work and back every day, either, so something has to give…