Sta Flo Laundry starch works as well as the more expensive stuff. Dilute to: 1 part starch to 4 or 5 parts water. Put the mixture into a spray bottle (the one you got with your expensive starch), shake well and spray away.
I can't find Sta Flo in the laundry aisle in the grocery store anymore. I had to go to Walmart to find one last week.