If he left it in original condition it might have been worth upwards of $300. With a blue LED he probably reduced the value to about half that. Come to think of it, that's also about as much as he reduced the battery lifetime.
BTW, the S/N is 8200. I asked him to check inside the battery compartment....
I have a Rocktron Deep Blue chorus that has a blue LED like that on it. Even in normal indoor lighting, it blinds you when you bend over to adjust it. Looks cool, but it does get annoying after a while.