Fitting a new 'solid' rear axle is easy-peasy, takes about half an hour as there is no need to be quite as 'accurate' balancing how much sticks out each side (plenty of 'leeway' with wheelnuts. in that as long as the axle goes through the nut fully it doesn't matter how much protrudes beyond it)
Freewheels do 'oscillate' a bit, are you sure the axle is bent (the axle does not rotate. it is solidly fixed and the wheel spins on the axle)It was leaning against the wall in my shed and rubbish had been piled on the rear end. I think its the axle anyway. When you spin the wheel the cassette rotates in a slight oval shape.