Yes, they are still avaialable. Don't recall the cost, but not cheap, in comparison to California where they sell them on every street corner.
Personally, we go to the KK store where you eat them fresh off the conveyer belt, they are fresh, hot and melt in your mouth.
It was only up until a couple of years ago when I had my first KK. I was imprssed and really enjoyed them. Ive had them a few times since. Well back in Dec we went to the BW bakery for the first time and DS got chocolate frosted and vanilla frosted donuts. I ofcourse had to "sample" them, LOL and I thought they were the best donuts ever! Even better than KK. So no, I dont prefer KK to BW bakery.
KKS are also found at the Roaring Forks at the WL and Captain Cooks at the Poly. My DD got two for breakfast every day during our trips. They are not that pricey at all. They were $1 a piece which is a bargain at WDW!