What is the best place to get them? I want celebrity ones like Arnold...

You mean like portraits non-BG and non-IWD?

i mean portraits that aren't in bg or iwd, but ones that are user created/edited .

Well, they have two sizes. Large and small. I'm not sure what the #x#'s are, but I'm sure you can find that out from one of the custommade portraits by BG or IWD. You get the portraits to the right size, save them, and put them in the portrait section of your BG folder. Then when your in-game just select custom, and they should pop up.