Also how do you trade using the forums? I only have two and they are probably common ones but I do not know. I read about how to propagate using the leaf cuttings and have some new ones started.

Rexes can be found locally at big box stores, local nurseries, grocery stores once in a while, etc. They can also be bought on line such as eBay, Logee's, Taylor's, and several other begonia vendors. Going to begonia conventions is another great way to add to a collection.

There is a trade forum here but I wonder if anyone uses it much. Why not post a trade on the main forum instead of a lesser used adjunct? It's like the picture forum - almost useless.

Here are some of mine over the last few years:

Kartuz and Lauray are two other good sources of begonias, but they don't seem to have a lot of rexes.