Hi! I checked into something and wanted to share. You can rent an ice cream truck (think Blue Bell...the ones that drive around neighborhoods selling ice cream) for your wedding! I think this is the route that I will go with. It fits perfectly with my picnic wedding!
The minimum to have them come out to Stillwater is $150 for a truck and around $325 for the cart. I was told that it's basically the cost of the ice cream is what they charge. So if you sell less than $150 in ice cream, you pay $150. If you sell more than $150, you pay the $150 plus the cost of the extra ice cream.
http://www.bigbellicecream.com/