The droprates for rare quality designs need to be increased. They are most likely well below the 0.1% blizz-like drop rate.
I definitely need more data, but I understand that the population online sits well above the 3000 player cap blizzard had on their servers way back when. But lets do a little bit of math for arguments sake.
Assuming the server has roughly 5000 players on a faction (which the server is well above) and that each player kills an 20 mobs within a 4 hour session.
5000 x 20 = 100,000 mob deaths within four hours.
0.1% x 100,000 = 1000 blue drops within that 4 hour period.
Even 1,000 feels a bit too high, but assuming a 14,000 server population that is close to 50%, there should be a lot more than 80 or so designs available in the auction house.
I understand that the population is very high and that it is probably a great idea to lower droprates overall on items in order to maintain the economy. But there rates might want to be increased a bit more. Players wanting 1/2 the cost of an epic mount is some insane price gouging due to the rarity of these design drops.
0.1% drop chance is per mob. doesn't mean you'll get 1 after 1000 kills. you could kill 1 mob and get a drop, or you could kill 1,000,000 and not get any.
not saying the drop chances don't need a tweak, but your math is off.