Thats how I grew up too. 1950's Case equipment. I can't walk well anymore but I can lean...but not well either.I forgot about the Steiner! The Husqvarna R322T is like a light-duty poor man's version of the Steiner.
The cheapest slope mower you're going to find will be an old walk-behind push mower, if you have the time and energy. The ones with high wheels in the back are the most maneuverable, but I don't think they make those anymore, and definitely not self-propelled on the rear wheels (the front wheels won't have enough weight on the slopes). Heck, my Honda pusher spins the wheels going up any decent slope.... still have to push it, just not as hard!
Growing up on the farm, we baled hay on slopes approaching 30°. We set the wheels as far out on the axle as we could, and had them filled with fluid. Ag bar tires are also key here. One of my jobs was to walk behind the small round baler while Dad baled the hay.... I had to catch the bale when it popped out of the baler, then turn it perpendicular to the slope so that it wouldn't roll down the hill. Ah, the smell of fresh-cut alfalfa!