you can go over the printing with a micro-pigma pen (permenent ink) and heat set like quilterella did-
but cotton/poly blends are everywhere (except your lqs)
they are mixed in with all the other cottons in the stores like walmart, hobby lobby, joannes-
alot of the broadclothes/solids are blends in the (big-box stores)
not all broadcloth is a blend-
you just need to read the end of the bolt and see- it will tell you the fiber content of the fabric on the bolt.
i have used some iron on labels- i heat set after filling it all in- had no problems.