One of the members of my quilt guild did a test using Best Press and several other different spray starches (Niagara, Faultless, and another one from LQS but I cant remember name). She cut 4 pieces of muslin, numbered each one, and pressed each using a different starch. We all had to vote for the one we felt gave the fabric the most stability--Best Press came in last. It hardly felt like the fabric had been starched at all.
I get the Niagara or Faultless at Walmart for less than $1 a can. Sometimes I find it in scent-free but don't have the issue you do with sensitivity.