I really have no good suggestions about where to get one from except maybe to order it directly from Wagner.
http://www.wagnerware.com/CatMainDetail.asp?Filter=PL&PLine=4&PCat=2 Notice that they call their smaller ones casserole dishes and sell them with glass lids.
Maybe these people here would know better?
http://www.idos.com/More Useless Information:
The last time I bought one new it was from Wholesale Sports in Edmonton Alberta. It was Lodge.
The one I had before that was from a thrift store. It was Wagner
I had two before that, one of those was a yard-sale antique with the Simpson's (Robert Simpson Company) catalog store logo on the lid and the first one came from a hardware store. I can not remember what brand it was.
All of them were no leg versions with rimmed lids except the Simpson's one which had a domed lid. It still worked fine.
The reason the earlier ones disappeared was that they were sold to antique buyers.
I don't seem to be able to find the flat lid with a rim for the Lodge or Wagner ones any more.
Yet the one I have has that lid and no legs.
No legs means it can be used on a stove.
If I need it up to have fire under it I can set it on rocks, a trivet, a grill or hang it from a tripod or something.
Do not buy an aluminum one ever.
The aluminum ones I tried were really dangerous!
Even worse than the fact they do not hold the heat well is the fact that they are too light to balance the food.
It makes them very tippy and extremely likely to spill.
The last thing you want is to be severly scalded by boiling hot water.
When I buy used cast and want to clean it I put it into the fire and burn all the grease and crud off. After it is cool I brush out the ashes and sand out any rough spots. Then it gets seasoned with oil.
Lard is the best, but almost any cooking oil will do. Wipe a thin layer of oil on it.
The idea is to get the oil soaked into the pores of the cast to seal it, and then keep it almost smoking hot until the oil has polymerized into a tough no-stick surface.
After that you should not scour with abrasives or use detergents in it. Just wipe it clean with a cloth or brush.
Once in a while wipe extra oil on it and let it heat to about 375 degrees (almost smoking) before cooking in it to thicken the seasoning layer.