Relocating air handler
I'd charge about 2k-3k upon how much was involved, for just the move of existing equipment. You're going to have to extend and reduce ductwork, re-run drains and copper linesets which include a pump down of the refrigerant and then a vacuum, extend and re-work electrical, etc. Having said that out loud I'd be more inclined to say 3k, not 2.
A new air handler can cost a few thousand (installed and warrantied) as well dependent upon which brand, efficiency, model, etc.