If you only have one leo, you should be okay with 1 dozen a week.(about $1 - $1.75 depending)
A lot of people use a "critter keeper" ($5) to house a small batch of crickets. Make sure you keep your crickets well fed & 'watered' at all times.
Food: If you look up "dr gecko" on google, you should be able to find the gutloading section. I've come up with my own version that is a little easier to make and keeps the crickets super loaded. Feel free to e-mail me for it. There is also a cricket feed by Flukers that we keep on hand, just in case.
Water: We've found that Flukers Gel water seems to work best, along with raw carrots. If you use water in a lid, chances are your crickets will be TSTL, and drown.
Supplements: We also keep a tiny plastic lid filled with a concoction of calcium, vitamins, high protein/fat mixtures and honey as a treat. (This is also great to gutload a select few crickets on in a seperate contatiner for a underweight lizard/gecko!)
We keep our feeder crickets in a 5 gallon tank ($10), several dozen at a time. In the cricket tank we have "cricket cardboard"-- which is really just clean, torn up, cardboard cup holders from a local take-out, for them to live and breed in. We also have three plastic lids for a food dish, gel water dish and a vitamin supplement dish.They generally live for about nine - fourteen days. They can live longer, but we try to keep the adults from developing wings. It's become a science for us, trying to figure out the cricket intake of our lizards/geckos.
We buy on average one dozen 'Large', one dozen 'medium' and two dozen 'small' every seven days or so, or as needed.
Our AFT eats around 3-5 crickets every other day, and we offer one cricket as a 'snack' on the off days. The Leo, we are still fighting with to eat crickets...we're having to trick her, and de-legging the crickets...which is not much fun and pretty sad.
Our other lizards go through the 'small crickets' like candy.
Hope this helped!
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0.1.0 African Fat Tail
0.1.0 Leopard Gecko
1.0.0 Flat Tail House Gecko
1.0.0 Long Tail Grass Lizards
1.0.0 Betta (Past away 3/17/04)
1.1.0 Cats