This a not-all inclusive list of potential suppliers.

CanadaAmmo: Decent price, great quality. Has the non-Americanized (which is really stupid looking) version of the TAR-21. Unfortunately, no STAR with heavier barrel and improved optics, although you can buy the ACOG sights from Trijicon instead.
Trijicon: Arguably, some of the best optics around, many with nighttime illumination but do not require batteries, and noted for reliablility.. Reflex sights DO increase targeting speed and acquisition, enhancing CQC shooting vastly. The ACOG sight is immensely popular with US military forces.
Blackhawk:: Militry, Law Enforcement, Corporate Security, and Outdoor Gear.
Galls.Com:: Uniforms and duty gear (gunbelts, body armor, etc).
Major Surplus And Survival.Com:: Militry surplus and survival gear.
BudK.Com: Knives and melee weaps; One would be best-profitted to obrtain working knives and blunt weaps from them.
¡Cheaper Than Dirt!: ¿Like guns? ¿Like shooting? Check these guys out. Gun accessories (including upper receivers for the AR-15 Series), ammo, cleaning kits, if it has anything to do with guns, even many gunsmithing tools, you name it, they got it. (Every single piece of gun accessory gear from the Skin Job Hunters page, came from them.)
Bond Arms: Produce high-calibers derringers. Home offices in Texas, USA.
Uncle Mikes.Com: Duty gear (gun belts). Possibly THE best on earth, but also one of the more expensive.
Quartermaster Uniforms: Cheaper duty gear, more apporpirate for the majority of you.
Brigade Quartermasters: Outdoor and military survival gear.
Surplus City: Bills themselves as the largest suplus store on the West Coast. The did have a de-milled mobile artillery peice (the cannon was replaced with what appears to be a boom).
Roadside Imports: Just found on the 'Net, they have a wide assortment of "spring-assisted" and automatic knives, some well known brand names. Also, they do have some standard knives and tools, but the emphasis is on spring blade type knife.
The Epicenter: General survival supplies, plus solar power systems and other items for long term events.
eFood Direct: Bulk food
OTHERPOWER: Alternate energy source
Gunbroker: Basically Ebay for guns
Deep Six: Diving supplies, including Bangsticks.
Swords 24: European supplier of knives, swords, and similar items, based in Poland
Penrith Survival Equipment: General survival equipment supplier, based in England
Tanksforsale: Has a nice selection of military vehicles, mostly Russian, including tanks (NOT DEMILLED, YAY!). Based in England.