It's pretty easy to get button makers (so that you can make buttons by hand -- not entirely en masse). I have had them purchased for a camp that I worked at.
Then you just need to print out a picture and make a button.
If you took the hit of buying the button maker, I wouldn't be surprised if there were plenty of people willing to pay $1 per button, or so, to help you make up the cost.
Then of course, there's always this issue (from my campus):
http://farm2.static.flickr.com/1025/147 ... 611c9a.jpg