I ride about 10,000 miles in 17 weeks, so that about a set of tires in about 4 months. That's three sets a year for those that didn't want to do the math!
That's why I have my own tire changer (it actually sits at my son's house since he's been using it more that I do. - he's into the mini-motos and sells tires/rims to the guys that race them - yeah, he trys to race them too...
)
So I watch ebay for "deals" on tires. Sometimes I score and sometimes I don't. I do try to have at least one set of tires sitting in my storage so I can swap them when I want and not have to wait on the tires coming from someplace and not being able to get the bike back on the road. Of course, I can always take my 2012 if I have to!