I am not an expert on mini-splits, but it seems a 2 ton unit is very over sized for an area of 672 sq. ft.

Take a look at Mitsubishi and Sanyo (Panasonic). They have good reputations but I am not sure if they are going to be any cheaper.

Does your DH have the equipment and knowledge to install a mini-split?

You really do not want to go with a unit that size. Here's a great calculator that can help you get the general idea of what kind of size you would need: http://www.northernac.com/newcalc.htm

Fill in the necessary blanks, and that can at least help with getting past this first option, and hopefully into something better suited. There is also a contact for Trane on their website to speak with someone about sizing the appropriate unit for your garage: https://www.trane.com/residential/questions/what-size-system-do-i-need

Hope this helps

The electric isn't the hard part about installing a minisplit--it is the copper line set and "fill"...

My understanding on minisplits is that most all of them are about the same with varying degrees of efficiency. If you are getting a single unit, single head, Trane is probably fine. We have a dual head unit as well as a ducted ductless system. The contractors who did our Mitsubishi also dealed in Trane. BUT, trane was unable to match the efficiency we needed for our local rebates. (They could have in a single unit system, but not in the system sized for our needs).

I'd say, you want to know about the efficiency.

If all you need is parts, because your DH is doing the rest (keeping in mind the hard part is the copper lineset), you can buy units online. Otherwise, price-wise, it seems fairly normal for what it is. (I do think it could be oversized...but then, with a garage, the ceilings are pretty high so the volume is larger than a normal 1 story house).

Not familiar with Trane in mini splits but a few comments.

I would not be overly concerned about oversizing as inverter mini splits can vary their output. As an example a 24,000 (2 ton) Mitsubishi heatpump model shows in their brochure as being able to throttle down to as low as 8200 btu (.7 tons) and go as high as 2.6 tons. The blower can vary it's flow from 388 cfm to 738 cfm. Typical AC systems have 1 speed that the compressor operates at (although there are more expensive systems that can operate at two or more speeds) . If indeed you purchased a larger system than needed in an inverter mini split it would operate at a lower effective tonnage and not present a problem.

Be aware that purchasing a unit over the internet will in most cases result in no warranty. Also, installing the unit yourself will in most cases void any warranty that there might be.

Regarding price a 2 ton major brand inverter heatpump mini split with a straightforward installation including a new 220 electrical line might be in the $3750 to $4500 range from an HVAC company.

Window ac unit? $300? Friend bought house style furnace/ac for garage. Works great. Money is nice. If u got it