Any of the old black Singers with the motor mounting boss can be easily converted to a handcrank. Sew-Classic sells reproduction hand cranks and spoked wheels if needed.
I don't know of any reputable dealers as such. There are members here who sell machines locally. I'm not sure if any have what you want and some don't like to ship because it's so easy for a machine to arrive damaged even with careful packing.
Another option would be to buy locally and test the machine before you buy.
Rodney