Nope, 30 is nothing in terms of b2b, and from what I've seen the standard 20-pack case of bulk drives from a manufacturer isn't generally discounted from 20 individual bulk drives.
The "way" to get a discount on a lot of drives is wait for someone like Newegg to have a sale -- example Samsung F4's were down to $60 back on Nov. 6 -- and then keep buying 5 at a time using different email addresses (accounts) but same credit card. You wouldn't get cheaper than about $90-$100/ea. if you were buying quantity 1000 from a distro.
Keep an eye out on black friday, and then also the last week of the year which is notorious for drives being marked down as loss leaders.
Yeah, really hard drives are so cheap these days that you'd be hard pressed to find a 'deal' on bulk purchasing from just about any vendor. About the only way to get any sort of a discount would be to buy directly from the manufacturer and then you would be talking about thousands of drives, not hundreds.