In stock right now at RedWolf Airsoft are the ProWin 36-round Gas Mags for TM G17 and G18... "ProWin are known for making exceptionally great magazines and the ProWin 36rds Magazine for Tokyo Marui Model 17 / 18 Series is a great example.
Now available at 18Airsoft is the Army Force Polymer Hard Case Movable Holsters for G17/G18/G19 Airsoft Pistols. Made of Poluymer, they can fit 2-inch Tactical Belts and can accommodate the pistols equipped with a Micro Dot Sight or Flashlight. Available in tan and black, what they have is for right handed shooters.
Most probably the deadliest looking airsoft Glock 18C gas blowback pistol we've seen so far. Laylax has customised the full auto Tokyo Marui Glock 18c GBB and kitted it with a SAS Front Kit, Fat Suppressor 150, Magazine Bumper and Magwell, and Tritium Sight. The result is a pistol that also has a feared name "Glock 18c Assassin's Custom" which the parts you can purchase at the Laylax online store.
Also in stock right now at Get Reload is the Gen 4 Full Metal Slide Hardkick Gas Blowback Glock 18C Pistol from WE. At US$86.00 you get a full metal slide with a high impact polymer frame, full trademarks, gas magazine compatible with the WE G17 and Tokyo Marui version, adjustable hop-up, white partridge sight and more.