the only ones i know of are as follows:
BrickLink
BrickForge
Little arms shop
and of corse you can serch eBay
in the store
Lego does not sell military Lego minifigures, however, a custom Lego minifigure site below sells them.
try brickarms brickforge and little armoury
Lego Halo as a theme doesn't exist. However, many people custom Lego to create Halo helmets, figures etc. Try typing it into eBay to see what it comes up with.
No, there is no Lego transformer. Only custom creations posted by people.
yes. I suppose so if you like Lego's because it sells Lego weapons,and custom Lego people.
Yes, you can. They can also be replaced with figures from your own collection.
A great place to buy Lego mini figures is eBay!
you just get some sharpies, turn them into Lego and build a figure. you could build any sort of person you want. it is simple. it takes 34 minutes.
LEGO doesn't sell military set . If you are ok with much lower quality of parts check out best-lock toys. There are companies that specialize purely in creating custom Military / Army Minifigures or Model kits out standard LEGO parts and some custom elements.
Many people think that Lego Minifigures are rare but they are certanly not!
The best sites to purchase custom Lego sets, is from either Firestar or eBay.