Not sure how it is where you are, but there are a couple places here that sell last years tires at a pretty good discount during the spring. I normally spend about half price on decent tires because I don't feel the need to buy the newest pattern available.
I agree, if you're going through a tire change anyway, go for a new one.
Only time I ever ran used tires was when a friend would change tires every year, and he only put about 500 miles a year on them. Same dude put new tires every year on his truck, and I got those too! Didn't buy a single tire for 10 years, loved it!
Ken.