Get some more bids. We replaced our 20 year old AC & furnace this summer. Those guys are hungry. There are numerous Carrier installers as well as Lennox (my favorite). You NEED to get some more bids then have them compete against each other.
Yeah those prices sounded high. I had a tech guy who does telephone stuff do some work recently. He had an issue with his house and went on Craig’s List and got a semi used system cheap.
They are hungry. Also search some of the online sites. In central FL I can get a 4 ton install for about $2500 after rebates. The furnace is more but search around on the web and also check Craig’s List. Guys are on there advertising deals.