I haven't gotten prices from Gary Creason, but I do have a 2004 rate sheet from TC Tours shuttle (based at the Touring Cyclist bike shop in St Charles). Their prices range from $60 for St Charles to Weldon Spring, to $360 for St Charles to Clinton. Note that these rates include 1 to 4 people and their bikes & luggage. So St Charles to Clinton is only $90 per person if you can find three other people to split the ride. For 5 or more, add $5/person and $5/bike (don't know what their maximum capacity is). Again, this is from a rate sheet dated 2004, so rates might have changed, but this gives you a general idea what to expect.
Here's a list of all shuttle services (using the "Plan a Ride" feature):
Regarding camping, here is a list of all campgrounds along the trail : campground list