Anyone casting their own might be interested in these:
Gator gas checks
Customers who've tried them say they're actually slightly better quality than the mainstream brands but a good bit cheaper. They come in a huge range of sizes; use the drop-down list to pick a size and see the pricing.
We currently have lots of 22 cal, 6.5mm, 30 cal and 35 cal and some 270 cal, 44 cal, 45 cal and 50 S&W cal.