I have picked up starch in a pump bottle at Walmart. I have seen both Niagara brand like this and Faultless brand.
Walmart on line has loads of choices, including best press.
Unlike Suzanne, my experience with making my own with stay flo is the pump bottle gets gummed up and doesn't work. I plan on reusing the pump bottle from the starches I bought pre-made to give it another try.