I have gotten out of the habit of doing this but it's one of the best money saving ideas I've ever used. Since the boys have gotten so big now and seem to go through twice the laundry that they used to it's going to be even better now. I also love this idea because I can use my favorite fabric softener without worrying or feeling guilty about the cost, the last time we used this the small bottle I bought lasted two years.
Buy your absolute all time favorite fabric softener, don't even consider the cost because it's going to last a long long long long time! In a small container with a lid mix a solution of fabric softener and water 1 to 4 ... so if you use 1/2 cup fabric softener use 2 cups of water. Get a new sponge and cut into 1/4s make sure the pieces will fit into your container. When you need a dryer sheet just wring most of the solution out of the sponge and toss it in the dryer! It only takes just a minute to mix the solution and no more time to deal with the sponge that dryer sheets. This works fabulously without coating the dryer lint screen with that nasty residue.
Just a note on that nasty residue... most people do not even realize that they have this!!! The weird fabric that the dryer sheets are made of sort of dissolves in the heat of the dryer somehow and coats the screen on your dryer's lint trap. Over time this causes the dryer to not work properly and the element ends up burning itself out because it overheats. I don't know for sure but I think it probably cuts several YEARS off of the life of your dryer.
To see if your dryer has this problem take your lint screen and hold it under running water. If it holds water instead of allowing it to IMMEDIATELY pass through it then you have already begun the gumming up process. Take vinegar with a few drops of dish soap and your cleaning toothbrush and scrub as much of that gunk off as you can and let it dry before you put it back in the dryer. Your dryer will dry faster without that invisible film on the lint screen too!!!
We used to have to replace or repair our dryer every few years. Finally an appliance repair man told me when I called because the dryer wasn't drying properly to check the lint screen this way and sure enough the dryer we have now is well over 20 years old and we've had it for the last decade with no repairs necessary.