Hi all!
I want to purchase the above said items for my keychain camera.any leads plz?

Which is your key chain camera , 808?, If this is real 808#16, you can buy Lens D for 808#16 which have An angle of view 120 degree from Ebay.com cheap. But if it is low price clones, you can't attach the lens module.

It's a low price clone whichi got for rs  :-\300/-

These clones are usually not the original H/W or quality, recently i have been in to various types of these cameras and learned a lot about them, And i am planning to buy a real 808#16 from ebay, for around 40$ (2400 ) - this is the price of original #16 (720p) . Adding lenses or different camera module is only possible with real 808#16.
 LensA , LensB , LensD are the 3 available lens types for the 808#16 in which LensD is fisheye(AOV 120degree), you can buy one of these cameras or lens modules from Ebay.com, price of camera is around 2000 to 3000Bucks (the original of course). To find out clones from original ,and to know all about #16, please visit chucklohr's website.

Are you in to FPV? Then this is surely not the camera you need.