The cost will depend on many things and that is best found out in your area. I would say for a couple it might work , I have no idea where a TV would go. You do not share any info about where it will be, is it a permanent home or for holidays but generally an achitect can be a big help with small spaces

Permanent retirement home. TV will mount on fireplace. We will do the construction as much as we can

In most areas of the country, the starting cost of that would be 150-200K, plus the cost of the land, plus the cost of the land developments like septic, well, power, driveway, etc. A frames aren’t very DIY friendly unless you own a crane, or have a whole football team of sons as teachers with the summer off to frame it.

They also waste a ton of space and materials on a not very efficient layout. Anytime the floor is the biggest part of the house, you’re getting short changed in livable space. Square is more efficient. Like maybe a double shed roofed structure.

We have 2 acres in the country and there is a crane business next door to us. Lol We thought we would build them on the ground and then put them up at one time. We would have 20 or so friends to help ( like a barn raising). We built our square house 20 years ago this way. It's approx. 1200 sq. ft. Including the loft

The only bathroom isn't very guest friendly. If anyone ever stays in the loft, I wouldn't want them invading my space to be able to take a shower . The same with dinner guests. If you only want one bath, it should be more of a "hall bath" type, and easier to access from the public spaces, or else you want two baths. I would rework all of the utility spaces for more efficiency, and to be able to add a shower stall to the powder room. There's a lot of wasted space there.

Also, you have the bathroom, a closet, the kitchen, and a breakfast area on the prime sunny south side of the home. I'd redesign that to make that the public spaces, full of light. If you keep the master on the West side, a porch on that side would be great to shield the home from the hot western sun. And it would be a cool spot for morning coffee. It would stay cool till just past noon during the day.

I don't see any stairs to access the loft?

The big part of the A will be full of Windows and is to the east where we will have a deck and a pool. The opposite side of the A is the West where we have trees to shade the house and only 2 windows. One in the master and one in the loft. The front door is in the dining room with a dormer providing a cover and 9' wall. The opposite side in the kitchen will be a dormer to allow for upper cabinets. All of our children live near by, so we don't even need the loft. We just decided to take advantage of the space for a queen size Murphy bed and storage. The loft will have a ladder type stairs. My app doesn't allow me to show the windows in the roof above the areas in the cathedral ceilings.

So loft guests have to shower in your private bath? Ew. And if you have friends your age who come and stay they gotta climb a ladder to get to their bed? I dunno, I think an architect could help here. And maybe I'm being dumb but how do you access the closet that abuts the kitchen wall? That laundry room is big, could you put the furnace/hot water heater in there also?

I played with your suggestions and came up with this. We really want an A frame. Do you think this is any better? We really don't want company. We have had children living with us for almost 50 years we are ready to be empty nesters lol. We are trying to make sure we can still access most in a wheelchair when the time comes.

Absolutely none of that plan is remotely wheelchair accessible. It is not designed to be retrofitted to be accessible either.

And it is a dark cave for the most part for the most used rooms. Closets do not belong on corners. Ever. That is high value real estate that allows you to have windows from two directions. Those should only be used for rooms that you spend the most time in. Not a closet or a bathroom, unless there is no other choice. There are other choices here. You just need a person of design talent to design this for you.