Heard of them? Sure!
Spotted shrimp are commonly available in the Pacific Northwest, so we get them frequently. I think they're found all the way up to Alaska. I've never seen them quite that large, though. Typically, we get 6-10/pound , and those are pretty big for shrimp (there's always a supply of smaller ones); the ones you're getting are quite rare, and you're paying for it. I usually pay around $8-12 when they're in season, maybe a bit less if I get them right off the docks.
We usually just steam them, squirt a little lemon on them when they're ready, and eat them with some fresh baguette and a cold Macon or low-end white Burg. Great summer meal. I especially like it when I get a few females in the bag with their eggs, which I love.
A more laborious way to prepare them is sort of Greek style: peeled shrimp covered lightly with a sauce of onions, garlic, tomatoes and lots of basil, reduced to thick, then covered with crumbled Feta cheese, and baked for about 20 min. in separate small baking dishes for each person. I'm actually making that for an appetizer tonight!
I'm using frozen shrimp though.