It's a trade-off...the feeder anoles are going to be loaded with parasites, unfortunately. Worming drugs don't improve longevity, either.
If the snakes will take FT, freezing the anoles for several months supposedly kills many parasites.
You might consider buying up lots of normal leopard geckos. They would certainly cost more ($15 ea wholesale), but they'd be a lot cleaner. I'm not sure how many animals you have to feed, though. You might be able to get a better deal than that if you find the right supplier.
There's always the option of raising your own. You could set up some groups in sweater boxes, and produce quite a few hatchlings every year. Probably not the most attractive option if you aren't already keeping lizards, though.