Best MILC for Shooting Figure Skating?

Another way to control costs is to start with a prime (non-zoom) lens. Nikon makes a splendid 180mm f/2.8 which might work very well at skating rinks. The autofocus version goes for $900 new and about $600 used. Your daughter couldn't shoot when the skaters were near her, but from mid-rink onward (approximately) she could get full figure shots.