I have a Misto as well, but in all honesty it doesn't do nearly as well of a job as store bought spray's. In fact I'm considering putting it in the yard sale box. I just watch the sales and when PAM of generic spray oil goes on sale for $1 a bottle, I buy.
I was doing hand oiling, as another PP mentioned, but I hate the residue on my fingers and using a paper towel to smear is also just another cost to factor in.
Alas, never hurts to try different methods to see if you can come up with an alternative that will fit for your lifestyle and needs.