I would say that number might even be a little high.
Ronnie and I brought the Bass Bus to Guntersville, towing Riskkid's boat and I think my total cost was around 600, including about 400 worth of gas.
Last year, staying in the campground with Jimzee and Pitchinkid, my total cost was considerably less even after factoring in the food for the Chicken Dinner.
I bet 450 would be enough for just about anyone to go on this trip, barring those flying in.