You don't say where you are, DrRod, nor do you say what you plan to do with the tractor, how big it is or how old.
There's one advantage to gas tractors that I value: Old, well maintained gas tractors are much easier to start in cold weather than old diesel tractors. The new diesels generally start like a charm, but temperatures down around zero, without a block heater made the old standbys from the 60's and 70's almost impossible to start without ether. Of course, if you live in Florida this is no advantage.
One gas tractor disadvantage, that's particularly acute these days, is that the larger ones (say 45HP on up) were gas hogs. They sucked fuel like there was no tomorrow. They'd do this whether they were being worked hard or not. In contrast a 50 to 60HP diesel is miserly on fuel consumption unless its being worked hard.
However, some of the smaller, more modern gas engines were easy on gas. The 3 cylinder Ford 2000s (about 35HP) from the 70's were in this category. They'd do alot of work on a gallon of gas. The little 2-cylinder JD40s from the 50's were good in this regard also. Probably if your gas tractor's engine displacement is in the neighborhood of 150 cu. in. or less gas consumption won't be too bad. If much bigger, watch out! I don't think you could afford to work a JD60 or JD-A these days...they're strictly show tractors now.
FWIW
Bob