$3,600 to install a 2.5 ton mini split in NC, less some rebates from the local utility (approx $350) and a tax credit from Uncle Sam (well see). Plus the cost of an electrician to wire the appropriate receptacle, approx $150.
As far as DIY installation, it depends on how complicated of an installation you require. Mine required some effort by the contractor to snake the line through the walls, down into the crawl space and out through the foundation wall to where the outside unit would reside. It sits on a concrete block. The inside unit hangs on the garage wall. He damaged some of the sheetrock on the garage wall which I attribute to the difficulty of feeding the stiff lines through tight places. He came back a number of times to repair the damage.
Looks and runs great. The only other thing I would do is buy better insulated garage doors, but in NC it is not a big deal.