Put it this way - you now have the option to buy a good second hand press, way cheaper than any press with castors..... And you'll have a bigger choice of options.
Heavy duty castors are not expensive - then you just need a decent metal guy to make some adaptor sleeves with a plate on the bottom, so they can be welded onto the legs.
Get some info to ask a metal workshop and get a quote. You want to know the weight of the press (look up the shipping weight), the number of legs and the size of the legs. Then tell the metal shop you want it to be super solid. They will be able to price it up for you and I'm sure they can source some lockable casters.
At least you then know the cost and can make a decision.