I have nothing but good things to say about OS engines. Also, a .40~.46 glow (nitro if you must) engine doesn't use very much fuel. A gallon should see you through at least 16 flights at 8 ounces per flight. If you fly every weekend on both days, that's about a gallon every other week. Most of us are ready to land with only 1/2 of the tank used up. Driving your car to the field and back probably costs more.
Now, when you start flying glow engines in the 1.00 + range, you definitely will join the gallon-a-day club and should consider gasoline. Gasoline is not only cheaper than glow fuel, but gas engines burn fewer ounces per minute to make the same power. The smaller fuel tank needed partially cancels out the extra weight of the gas engine in a large plane.