Try Red Bird Service for Ferric Chloride. They stock a few
different strengths (10%, etc.).
Red Bird Service is a small company making chemicals related
primarily to some industry other than metalworking. However, I have
them make some custom blended chemicals for me. I just called, told
them what I wanted, they talked about it, called me back the next day
and gave me a stock number.
Wonderful company to work with. Very high quality, fast, they take
care of all the shipping hassles for hazardous chemicals and don't
cost much. They work in low volumes. Most of the blends I order are
only a few gallons a year in volume.
See www.redbirdservice.com or 1-800-428-3502.