Complete 700 GPH overflow kit with glass cutter, etc... $79.00
glass-holes.com
Already emailed em waiting for a ball park otherwise we've outlined a VERY cheap and not terribly laborsome way to do this. We can do it for 7-8 dollars an overflow(counting bulkheads). I'm waiting to see if glass-holes can do something in the neighborhood of 20 an overflow, Glass holes does have good prices on glass cutting hole saws though so probably grabbing those from them at the very least.