Again, it was a few years ago when I priced 9R22.5 tires, Yokohama I think they were, a reasonably rough tread for the rear and normal straight tread for the front.
I wouldn't buy the cheapest tires you can find, because even those will be expensive and if they turn out to be lousy you're kind of stuck with them. I'd buy reasonably priced ones that your tire dealer recommends, preferably a brand you've heard of and people say good things about.
Again, take a look for used ones if you find a set for a few hundred and they look good it's probably worth the chance.
Grigg