First, I want to thank everyone for your great suggestions re: the tortoise shell sconce situation. However, I feel I must clarify a few points (I think I was in a hurry when writing the initial post so didn't explain myself very well). The tortoise shell sconce I saw at the flea market was FAUX not real, and that's what I'm looking for, and it was painted gold which I really liked - the texture and the shine. I don't really love real turtle/tortoise shells because they skeeve me out a bit when I look at the back sides and think of the poor fellas who used to live in them. These shells used by Kelly Wearstler at La Marea restaurant in the Tides Hotel in Miami are all made of resin . . . that's what I'm thinking of using - not the real deal.

Secondly, I saw the sconce at the flea market on a Friday then returned on Sunday to see if it was still there, but alas it was gone. So, I would've been happy with one, but you snooze, you lose. Thus, my obsessive searching for something similar. As some people suggested, and as I thought about myself, I could just buy some resin shells, paint them gold, and then have them made into sconces.

I found this set of two large (16" tall) resin tortoise shells on Amazon for $127 . . .

not a horrible price, but if I'm going to have to pay to have them made into sconces, not great either.

Then, don't laugh, but I found these on the PetSmart site for $17.99 each . . . they are "Shell Hides" that you put in your aquarium for your critters to hide under or bask upon. Hmm.
They're a bit smaller (12" long) and apparently made out of a sand-based composite that retains heat. Not sure that's the best idea for sconces. Don't want hot shells on my wall. Obviously, the colors aren't great either, but I think they'd look cool painted gold or gold-leafed.

Then, while blog and internet surfing, I found things that just sort of resembled tortoise shells. There's this Banana Leaf Tiger Bronze sconce from LampsPlus.

At $299 each, once again, out of my price range, but kind of neat-looking.

And last, but certainly not least, did everyone see this in the D Pages?
I'm sure these are way out of my league price-wise, but aren't they cool? They're African Bowl Sconces made by the forward-thinking lighting geniuses at APPARATUS. Love them.
Okay, so back to reality. I believe the first option is probably the best, but I'm going to keep looking just in case. In the meantime, I need to search out somebody who can convert anything into sconces. I know you all are sick of hearing about tortoise shells by now, so I promise my next post will be about something totally different.