I started thinking last week that maybe we should get a couple of calves this year to train as oxen. It will be several years before they can really work, and I think future-me would appreciate it if I took the initiative and started the project sooner rather than later. The difficulty is that oxen are worked in pairs, and our pastures just aren't big enough to support two oxen and a beef steer, not to mention hay for them plus the goats during the winter. After much thought, I reluctantly tabled the idea of oxen for a later time.
However, just a few days later our downstream neighbor came to visit. His family owns the property, but they mostly just use it for hunting. It's a huge pain for them to keep all the grass mowed down, so he offered free grazing and mowing to me. There are a couple of pastures that are too narrow for tractors, so the local farmers won't cut them for him. All told, they have enough grass that I could raise far more than three cattle at a time, so now I'm seriously looking into starting oxen this year.
From what I've read, dairy breeds (or multi-purpose heritage breeds) are preferred for working cattle. I could easily pick up a couple of Holstein calves for less than $100 each, but I'm leery of that breed. The breeders have focused so much on milk production that I wonder how well they hold up to work. Then again, since I've never trained oxen before, it might be best to start with cheap cattle, knowing that they'll probably have a shorter working life than other breeds.
Up near Tappan Lake I saw a farm with Dutch Belted cattle, which are a little known milking breed. After reading about them, I think they bear looking into. They're probably out of our budget at this time, though.