Fuel is ranging from $3.50 to $6.00 a gallon at the moment. I just bought 3 cases of Phillips X-C (12 bottles in each case) for about $95. Something makes me think you'd need more than 3 cases
Not sure where you'd be able to rent an AN-2 tho'. I've seen plenty of them rotting around various airports, but few flying, sadly. If you're going to be that nuts, how about a Beaver, preferably on floats?