I would get .223 Chest Pouch (unless you have .308 system) for simple things. It will take AK or AR mags and also hold a pistol, radio and other stuff.
Molle compatible gear is very expensive compared to some others.
The M4 mag pouches made by just about everyone (Eagle, Blackhawk, TAG, Maxpedition, etc) will hold most any service sized handgun, with or without a light attached.
The bigger TAC V1 type vest goes well with most any pack and holds 6-12 mags and other equipment. I see them at gun shows fairly often for $50 or so. Look around online for good deals but don't get cheap web gear. You will be sorry. Avoid paintball stuff.
Blackhawk has the CQ holsters that are Molle Compatible. The Bianchi UM84 system is easily and quickly mounted to a belt, Molle/Pals pack or extended to the leg.
Bianchi M12 or UM84 system is best LBE holster ever made. Extremely durable and totally amibidextrous. Made for many different guns. The later models with the solid trigger support are more secure if your flap pops loose. The earlier ones will accept many different handguns. Pretty spendy but they are good.