I'm with Bruce. I use Repashy's Superfly for my cultures as well. ( an order can be placed directly w/ Repashy)
Tried many brands and recipes; didn't like any as much.

IMO - this is one of those expenses we just can't skimp on ---- don't want to run out of food !
You want to ALWAYS have at lest one full blooming back up....and others in different cultivating stages
Because, if and when they crash ---they crash and then there's none !!!
We need to plan ahead and have a ready made source of FF you can get with in a day or two.
Keep the bag of Repashy in the frig between culture preps.

Practicing is a good idea.

Juvenile leucs will need the smallest Drosophila melanogaster
When they are adults they will enjoy D. Hydei.
However, sticking with just the melanogaster would be fine.