Not sure where you are located in Maryland, but try Tropical Fish World in Gaithersburg, MD. I saw some Peacocks in there the other day. Somewhat large, but not 10", however, they can pretty much get what you need and will tell you what they will charge for them.
I asked specifically for a Black Ghost Knife. All the aquariums in the area sell them for $35+. I asked him if he was getting any in, and he said he would order some, asked what size I wanted, and what size would cost what. I told him as small as I can get it and he said $15-20. I'll take it!
There is a huge Koi pool as well, kind of nice to take a look around in there. The store itself is not huge, but usually has some pretty cool fish and monster koi.
Almost forgot, they have a huge glass tank built into the wall. Not sure the amount but usually has huge fish, but last I saw it had a nice FW Stingray, about 16-18" or so, with a couple other fish.
Hope this helps.