Try Quinn Violin Shop or one of the other string shops in your area. Local is always better if possible because these basses will probably need some setup and subsequent maintenance work.
Also, you might want to check out Ideal Music in NYC,
www.bassesonline.com , the guy who was liquidating his late father's vast supply of stringed instruments. He had a large number of fractional basses at one time but I don't know what he has left at this point.