We sold our "big" boat last fall after 22 years of boating.
Our 1st was a 40' houseboat similar to your picture. 14' beam, single 150HP outboard. Great for a weekend cabin, lousy if you actually wanted to go anywhere unless there was absolutely no breeze. I'm not talking about wind, just a breeze. With a flat bottom and that much area on the side, the smallest of breezes and you were white knuckling it around the dock or any other objects that you didn't care to hit.
After a ~150 mile trip, we decided that we were getting a different boat or a different hobby.
We traded for a 36' Gibson house boat with twin 350's and V-Drives. What a difference. Speed, handling, manuverability, but still sucked in the wind. We kept it for 8 years, put around 800 hours on it and a lot of miles. Great boat, but, it was like driving your motor home every time you wanted to go for a ride. Still fun, but we found ourselves sitting at the dock when it was just the 2 of us. Since I was the Captain, I wanted something more enjoyable to drive. (BTW, my wife is the Admiral)
Traded boats with a couple we had known for several years who had a 34' Sea Ray Express who used it like a cabin. All they did was sit at the dock and were looking for something more suited to floating instead of boating, so we made a deal in 2005.
Kept the Sea Ray until last fall, put almost 1000 hours on it. Probably going to miss it this spring. Or not.
Things to consider-
Slip fees: Around here, $1200 to $2500 per season.
Winter storage: Here, about the same as the slip.
Power: Some marinas include the power or have a flat rate depending on your boat, some are metered. Ours was metered and ran about $100 month.
Insurance: You will most likely have to have a survey done on the boat before you can get insurance. Survey costs are usually based on a percentage of the value of the boat, so I would expect possibly $1K to $2K. Our insurance was ~$600/yr with discounts for Boat US membership, multiple boater's safety courses,(Not a bad idea, and especially if you take them in the winter. A good reason to hang with other boaters) and the fact that I had zero claims in 22 years of boating.
Winterizing: 3 cases of RV antifreeze, a day's work, fogging oil, power washing the bottom. About $150
Spring: Sand and Bottom paint at ~$150/gal, wash, buff, wax.
So, We're closing in on $5K of annual expense with no labor, but we haven't bought the boat yet.
Sales Tax: May not apply in your state, but did here to the tune of about $3K
Depreciation: Our boat's blue book went from $52000 to $18000 in 12 years. Ended up selling it for about 1/2 the book value. It is a buyer's market, especially in the fall.
Fuel: Our Sea Ray got between .6mpg and 1mpg. Notice the decimal. That's not a misprint. 32 gallons per hour at cruise.
Annual Maintenance: Oil change was 18 quarts of oil, 3 filters (2 454ci drive engines and the generator), 19 spark plugs (gennie was a 3 cyl), 3 fuel filters and 2 water separators. Took a full day of contortionism to perform the work and a week to recover.
Spiders and other bugs love the water, so you'll have to wash it everyday if you want to keep it looking good. Waxing it will take several days.
The "Break Out Another Thousand" is conservative. For us, that was a trip to the gas dock. Other things to remember are "The only thing that works on an old boat is it's owner" and "The 2 happiest days of a boatsman are the day he buys it and the day he sells it". I can attest that all are true.
Marinas are like small towns with their cliques, politics and bullies. Talk to as many people as you can before deciding on one.
We had some of our best times while boating, made a lot of great friends and spent an enormous amount of money.
I don't regret any of it, but I am glad we are out of it. It is a lifestyle that consumes a lot of your time and resources.
I have seen a LOT of people buy a boat without an idea of the costs involved in both time and money, lose interest in a few months and walk away with a greatly lightened pocketbook.
I'm not trying to steer you away, but please take all of this into account and do your due diligence before you decide on anything.
Good Luck on whatever you decide.