I can get 5 gallons of a 50/50 nitromethane/methanol mix from a local VP Fuels dealer for $90.  I can get 5g of methanol for about $35 bucks.  Is this a good price and in a form that will be easy to mix to the proper proportions for boat and plane fuel?  Will a local automotive dealer carry castor oil, or would i be better off trying to make a castor synthetic blend? Where can i source both the castor and synthetic oils?

My local hobby shop sells Morgan Fuel Cool Power 30% Heli fuel which is a full synthetic fuel mix with 23% oil.  The Morgan fuels guy told me that the higher oil content will likely shorten the life of the glow plug.  Is this true?  Woudl i be better off just buying the heli fuel or trying to go ahead and mix my own to get exactly what i want for my boat, 30% Nitro/18% Oil, and for my planes 15%nitro/18% oil?