Main cost of neodynium:

* Magnets themselves

* Support structure for a heavy generator

* Energy 'iron losses' in magnet hysteresis.

Main costs of superconductors:

* Superconducting material

* Upfront cost of chillers

* Energy loss in chillers.

For bigger and bigger turbines, superconductors will always win, since the material is cheaper, and chiller cost and energy loss scales with the power generated ^ (2/3), whereas the support structure needs to be both taller and stronger so scales with ^(3/2), so superconductors always ends up eventually cheaper.