Hello Wadella, Weeping Katsura is a beautiful tree, very desirable in the landscape and not planted often enough.
Beaver Creek Nursery (www.beavercreeknursery.com/ lists Ceridiphyllum japonicum 'Pendula' in their growing catelog. they have a wholesale and retail side.
You might also try contacting the Illinois Green Industry Association (info@illinoisgreen.net).
Sincerely, Richard Hentschel
Sincerely, Richard