MRHELLO....yes they are usually sold by the pound.
There have been reports that red swamp crawfish can burrow into dams and possibly cause problems for pond owners. Others report they've added them to their ponds without problems. I assume the general consensus on Pond Boss is that they should not be added to our ponds.
Paper-shell craw-fish are known to cause less problems, but they are not as readily available for us down South as the red swamp craw-fish. This company ships Papershell Crawfish:
http://www.smithcreekfishfarm.com/productdetails4.cfm?product=live-fish-crayfishSome states classify red swamps as an invasive species. So just do some homework before you decide and know what you are getting into.
This year I added a few to my upper pond that is really more of a tank without a dam. They may find their way to my other ponds or they may not. If they do, I don't see it as the end of the world....but again just make sure you read up before adding them so you are aware of the pros/cons.
I bought mine at a local Asian market and I got a big grocery sack full of them for under $20.
This place sells them local in Dallas in larger quanities.
http://www.cajuncrawfishco.com/products.live_crawfish.aspVideo:http://www.youtube.com/watch?v=18UFiCf5g1M