The Energon Pub

I'm currently bidding on a Masterpiece Megatron (MP-05) that's in very good condition, but the thing is that it doesn't have the pistol (the one that kills optimus!) where's a good place to start looking for small accessory pieces like this?

Probably keep watching ebay. I am sure people with broken MP Megatrons put up accessories for sale. Maybe check the Buy/Sell/Trade forum here. He is being rereleased, I don't know how much you are willing to spend on ebay, but you could just get a brand new one.