+1 for JTAC Supply as Maverick656 noted. RB Precision only has a 10% discount from retail.
Most Blackhawk "distributors" just have a portal link on their website that takes you to the actual Blackhawk website with the banner of that distributor. These distributors can designate the percentage discount from MSRP that you get by ordering through the portal. Most common is a 10% or 20% discount off of MSRP. When you place your order through one of these portals, it goes directly through the Blackhawk ordering system and usually drop ship directly from Blackhawk. Basically, you use a middle man to get a discount instead of ordering factory direct and paying full price.
ETS Supply usually has some Blackhawk stuff on sale and good prices on the rest.
Every blue moon, Quantico Arms will sell Blackhawk gear for 35% off. I'm waiting...
-Randy