I buy skate whenever it's available (& looks good, of course - lol!). Do make sure it's been prepped, as getting the meat off that wing cartilage can be a pain in the you-know-what.
My favorite way of preparing it is a sort of "piccata" style. I dust the pieces with lightly seasoned flour & saute them in equal amounts of butter & extra-virgin olive oil. I then remove the fish & add a little fresh lemon juice, a dollop of dry white wine (Pinot Grigio is a favorite), & some capers. Allow that to combine/cook down a little, & then pour it over the fish. A green salad, some sauteed potatoes perhaps, some crusty bread, & more of that wine & you're all set.
As far as the flavor - it's tender & delicious. If I had to compare it to something better known, I'd say sole or flounder with just a touch of scallop sweetness.
And as far as sources, the Whole Foods market chain frequently carries it.