www.sableco.net is an awesome dealer to buy from. He sells the entire Surefire line. He has some of the more common 2 cell M95xx lights for under $200. He also only charges actual shipping, not some inflated shipping and handling costs.
I really think the extra money is worth it. The weapon specific lights do more than shock isolate the bezel. While the shock bezel may be the most improtant difference in some people's minds, there are other differences as well. Weapons lights seperate the batteries from the bulb. This will prevent your batteries from banging into the bulb with every shot.
The G2 you mention is a wonderful light. But it is not a weapons light. Surefire does not reccomend you use it as such. Is this merely because they want you to spend the extra money for their weapons lights? I have read some people on the board make that very statement. I dont buy it.
Do you need all the precautions offered by the weapons mounted system? Ultimately thats up to you. Clearly there are members of our board who think you dont need them. Some of them have used hand held lights on their AR's for quite some time without a problem. But under what conditions?
What you expect to use the light equipped rifle for should also play an important role in your decision. Duty guns, guns that you may depend your life on, and anything other than the dedicated range rifle, IMHO, deserve the additional security and durability built in to the Surefire Weapons lights. For rifles like this, its not the odds that matter, its the stakes!
They are some serious lights and cost some serious money. There is nothing on the market which come remotely close to even approaching Surefire's designs, durability, versatility, cratmanship, quality material, customer service etc. I'll own nothing else until another company can get it together.