As others have said, don't pass up a good gas burner. I have a 1973 Massey 135 with the Perkins gas engine. It would be close to your price range. I had a diesel model and loved it but couldn't find a diesel to fit my budget when I was looking 7 years ago but I did find a gas burner and bought it after some research. Couldn't be happier. I had a MF135 diesel years before and this gas has every bit the power. And the MF135 is one of the most popular tractors ever so parts are easy to come by.
As far as the ethanol issue; all we have around here is 15% ethanol but I treat every tank with Seafoam additive and have ZERO problems even though it sits for months at a time now that I have a 2nd tractor. The longest that I have let it sit is about a year. I turned on the gas and let the carb fill, pulled the choke and it started on the first turn. Seafoam will actually dissolve any carbon in the cylinder also. I started using it because of carbon issues in one of my motorcycles that would make the valves stick. I used to have a run-on (dieseling) issue on the Massey since the fuel cut solenoid on the carb was disabled by the PO but since using Seafoam it has never done it. I treat all the gas that I use in my motorcycles, lawn mowers, chain saw, brush cutter, etc. and I don't have to take the carbs apart and clean them every time I want to use them anymore.
