If you don't mind frozen, big black tiger prawn you can get it from Asian supermarket EUR22 for 1 kg. These are the same prawns served in most of the Chinese restaurants/take away.
Just bought some to-day in Iceland. They are excellent value @ €7.09 and you get 40 in the ring. It includes sauce but not particularly keen on this - just make your own with mayonnaise (light of course!) and tomato ketchup. With brown bread and nice glass of wine ....................