Depends on where you go of course,etc...around $30 - $50 a wheel or so. (Think I paid just under $40 for the last one I had cut and rewelded)

The only issue with going from a large backspace to a more shallow one, is the area on the outer where it was welded can show if you go back more than the width of the center. Depending on who/how cuts it out, it may or may not polish out.

Just depends on how far you move it though of course.