Monkfish (called Rape in Spanish) is super appreciated in Spain. It's sometimes called fake lobster. I't is very tasty, white boneless meat, and most of the fish can be used to make a great fish stock.
I don't know where the market is, but that is a pretty good price.
HEB. Really big here in Texas. It's more "premium" than Walmart at usually comparable prices, though they are more food focused vs. carrying everything.
I worked in a fish market for many years, and the story I was told on why it got the name of fake lobster (or poor man's lobster as I heard it called) is because it has a similar texture and its mild flavor allows it to take on stronger flavors it's cooked with - like lobster. So you take a bunch of monkfish and cook it with some lobster, and now you've got a bunch of lobster meat. I've also had it wrapped in prosciutto, and that was very good.