From what I remember reading, he did buy firearm stuff off of e-bay, but none of the items were actually used in the shooting. Why e-bay decided to pull the plug is beyond me. I have the feeling that they are anti-gun. Firearm stuff is banned, but not black powder stuff (well, the last time that I looked that is!)
As much as I hate using them due to the anti-gun stance, I still do if the price of the item warrants it. (buying - I haven't sold anything on there for a few years.)