Looking for any information regarding value on a Double Eagle.

I have a line on one, but unfortunately I don't know that much about them or this one in particular. I do know that the major problem was with the decocker and to look for the MkII/Series 90 rollmark. Is there anything else I should be on the look out for?

I should say that I am not particularly interested in it as a keeper, but more as an investment or possibly a project. They are asking $525 which doesn't seem outrageous, but is it all I should expect to be able to get out of it later?

As I said before I do not know a lot of specifics right now, ie condition, production date and the like.

Any help is most appreciated.

Thank you.