I think the rescue groups make their requirements so onerous to make people think twice before making an impulsive adoption. Some of the rescue dogs may also come with “baggage”.
Newfs are more expensive at the vet because of their size - heart worm medicine in particular - but that cost estimate is way too high. I think the $300-500 range is about right also.
I washed mine with a hose outside. When they were little we used the bath tub, but they can clog the drain… If you take a newf to the groomer, expect to pay a small fortune (up to $100 for a wash, comb out and dry). They have a double coat, the outer being almost waterproof, the inner very thick and fine, so it takes effort. Don’t really need the conditioner/detangler if you don’t want to use it. You don’t really need to bathe them frequently; you can dry out their skin and cause skin problems. They shed a little all year, but about twice a year they blow their undercoat, so a undercoat brush/comb is very helpful. Expect some intensive grooming and LOTS of hair during that time (they can burn out your vacuum cleaner motor!). Really, I can not emphasize this enough - there will be LOTS of hair. It will come out in tufts. It is very fine and fluffy and will float through the room. When my daughter was just a baby, she was crawling and drooled a little because she was teething, and she looked like she had a black beard. If you are not diligent with grooming, you can get some terrible mats. Don’t suggest shaving them down because it will eventually mess up the outer coat. However, I will admit to shaving my newfs when they got old because they were arthritic and the grooming was hard on them (one lived to be almost 14 yrs old - very old for a newf). Scissors and thinning shears are for making them neater (trim feathers, ears, feet), but not really necessary if you aren’t showing. The breeder should be able to show you the basics of grooming/trimming. Also expect drool. Our Newfs had “tight mouths” and did not drool much, but some can be faucets. They all get long drool strings when you have a tasty treat and watch out if they shake their heads! They also like to stick their muzzles all the way into their water bowls and come up dripping. Oh, and they like to play in water!
We did crate train ours and did have a giant crate. Again not necessary, but it does make house training much easier. You could probably get a used one for a decent price if really needed, but a small room with a tall, sturdy gate may be all you need.
I would really suggest budgeting for some obedience training. They are BIG dogs and can easily drag a large adult man and knock someone over if they jump up. Our bitch was about 120 lbs, and our male was 150 lbs. Puppy classes are also great for socialization.
Newfs can be a lot of work and cost more to own then many other dogs. We have owned a variety of dogs over the years - doxie, shih tzu, golden, welsh terrier, Aussie and Newfs, and hands down, the Newfs have been the best ones for us. The sweetest, most even tempered, laid-back dogs that would place themselves between their people and a stranger, never aggressive and very tolerant of kids.
I dunno, my current dog doesn’t have a crate and he was quiet when he had surgery last year.