So, i need flashlight with pressure switch. Mounting it to my airsoft gun. What model? Where?
Do you have, the mounting equipment? If so what size flashlight will it fit. If not, will you need a barrel mount or a rail mount. And how much would you want to spend.
this is budget light forum lol.
anyway, the first company which pops into my mind is EagleTac .. because they offer lots of accessories, drop-in modules, FREE lifetime warranty, and is a specialized American company with fantastic reputation on the flashlight forums. And their products are reasonably priced; not overpriced at all.
SureFire (expensive), Olight (nice), 4Sevens (overpriced), Fenix (afaik), a.o. offer this type of products too.
So, no budgetlights, where i can put pressure switch? I dont have any mounting accessories yet.
This is a good mount for you, it is a rail mount with a barrel to rail mount. It also includes the pressure switch.
These are some good flashlights you can use with the mounting equipment.
Choose a flashlight with L2 in its name, the pressure switch only fits those flashlights.
look for the batteries and chargers if you need some. Most of the L2 flashlights uses 18650 batteries.
Seriously, get a 2011 l2 from solarforce-sales.com and their pressure switch. Then get a 1 mode p60 drop-in. This is what im doing for my ar-15 
For an airsoft I wouldn't spend that much, an Ultrafire 501B with an R2 drop in and an aspherical lens sends out a beam 300 yards. I can clearly see my target at 300 yards through a Nikon 3-9x40 with this setup. I am using a Hugsby light and switch due to the recoil but the Ultrafire setup should work fine.
I think this setup would be perfect for an airsoft no need for the aspherical lens because you aren't reaching out 300 yards.
Get a Solarforce L2T or L2P along with their pressure switch. Good quality and a good budget light and switch. They have various mounts as well.
http://www.solarforce-sales.com/product_detail.php?t=FA&s=18&id=65