The problem you are going to find is in that 40' span. That in itself is not a structural problem, but it has a big effect on pricing. Anytime you start making spans greater than 20', then things start to get more expensive.
I estimate about $35,000 thou for one of those tin covered pole barn building kits. Another $5,000 to have it put up if you chose to not do it yourself. The slab alone will have over $4,000 in mud plus another $1,200+ in labor. I see you're in Bend, so I would recommend both heating and air conditioning. That means lots of good insulation.
Electrical service can be costly. Not the doing it yourself wiring in the building part, but the cost for the wire to the building, and the trenching to get you to the pole for service.
I'm assuming of course you live on the edge of town. No residential neighborhood would let you put up a 2,400 square foot shop. Not the ones in Bend from what I remember anyway.
I'm going to guess for a super simple no frills building that is comfortable to work in no matter the weather, $80,000 at the minimum. That is pretty cheap if you think about it. Of course, I'm a bigger wimp than most, so I like my workspace to be super comfortable.
David