This post on how long spices really last and how to find spices less expensively is well worth the read. There is also a link to making your own spice mixes.
I've got 4 little "baskets" full of jars of spices in my kitchen cabinets right now. The only "blend" I buy is lemon pepper. It's easy enough to blend my own for other seasoning mixes--and I just save my old spice jars to hold them. An old oregano or basil jar is great for Italian seasoning. When a cinnamon jar is almost empty, I fill it halfway with sugar and have one of the kids shake it up. Instant cinnamon-sugar for topping waffles or muffins!
Spices are pricey, so any little way I can save on them sounds good to me (here's one that wasn't mentioned: buy it in bulk and share with a neighbor!)