When i first saw it i thought you did a good job getting the hub off, most people struggle with it. Then i kept reading......
I can't tell you the cost of a hub and axle, you will need to hit up the dealer and see what they have to say. The job isn't hard, but it isn't easy either. You will need new bearings and a seal too.
I guess it aldo depends on what you use the machine for. If it's home use and you are happy to have a stab at repairing it, there is a way i can think of that may work. I'm sure OldMachinist will want to smack me over the back of the head. Most machinists don't like using bolts threaded along the join of a shaft, but it can work.
I don't know how hard the axle is either, so a drill bit may not touch it, but i'd see if the taper still fits pretty well, put it on and tap it in place, see if it's pretty solid. If so, i'd get some quality loctite, clean both surfaces and put them together, even use the bolt to push it in place. Then drill a hole along the join of the taper to act as a key. Thread it and install a grub screw, install the main bolt and hopefully it won't loosen up. Make sure the grub screw goes along the line of the taper so you get more surface area.
Hopefully some of that makes sense.
If replacing the axle, hub, bearings and seal is affordable, i'd go that way. You have nothing to loose with the other option, if it doesn't work, you have only lost some time.