There is one quilter who always answers in the starch thread. For the life of me I can't figure out who she is.
She says she uses a paint brush and brushes the starch solution onto her fabric, the a couple minutes in the dryer, then she presses them out.
I, unfortunately, have never been able to do that for myself. I buy Sta-Flo. It's a blue bottle of liquid, concentrated starch. It's incredibly cheap compared to the spray starch and you can mix it yourself. I use a regular Dollar Tree spray bottle with measuring lines on it. I use a 1:1 solution. It's a 2 quart bottle so it makes at least 4 quarts of solution depending on how strong you want it. I used it on 8 quilts last year and didn't get low until I started this one for this year. It's a wonderful time saver, I love how it makes the fabric stiff. I find it's helps me cut more accurately and my seams fit together much better. Since I always wash my quilts after their quilted, and I don't store them forever, I never worry about bugs getting them or anything like that.
We were a one income house for a long time and I couldn't afford to get fabric when I wanted to notions or pattern books or anything like that. That starch is VERY economic.