The title says "a Crestie", which to me implies you have only one. Breeding crickets for one gecko is totally impractical unless you don't have a quality local supplier. I have one 6 month old crestie, I feed it crickets every other to every third day. I just go to the local mom&pop pet shop and get twenty crickets for $1.09. I feed him two to three appropriately sized crickets at each feeding, thus my supply of twenty (which is usually actually thirty since they don't really count them), lasts for at least 2 weeks, sometimes 3.
I put a small dish of the Repashy Gutload, plus a small dish of Fluker's Total Bites sitting in water into a kritter keeper with some egg crate, and voila.