After seeing Mat's Deep Sea Siren avatar the other day, I decided that I just had to have one. I set off in search of Grendel's Children, which is the name of the shop where he found it, and I have to say, the place is amazing, but also amazingly hard to find! The Deep Sea Siren is only 90L$ if you can believe it. It's by Flea Bussy, and comes in purple, blue, green, yellow, red, pink, orange, and teal, including everything you see here plus an AO. I just love its lithe flexi movements.
The shop itself is lovely, and sells a variety of avatars and accessories, by multiple artists, including the illustrious Psyra Extraordinaire. Many of the avatars are quite affordable by recent SL standards.
The selection is amazing. Do visit.