You could make it.... I made some once ages ago and it was easily as good as buying from a store. And it's mostly just fresh popped corn and brown sugar, which the ingredients for a cheap. Try looking up a recipe! You can also make it in advance so no last minute stuff.
If you're budget conscious at all, I definitely recommend making it yourself. It's very inexpensive and a nice way to put a personal touch on favors. It takes about an hour to bake (so the caramel part isn't so tacky/ taffy like) but you can make a bunch of it all at once. Not very difficult either - just make sure your pans are big enough to hold the popcorn. Also, marissa_claire is right - you can make it plenty in advance so it's not even a thought near the wedding day.
Re: caramel popcorn
http://www.instawares.com/gold-medal-bulk-carmel.gmp-2427bl.0.7.htm?LID=GGLE&ci_src=14110944&ci_sku=GMP-2427BL