Magazine help

[Dave Sanders]

I have a guy who wants to sell this magazine, and I am not sure what to offer. He has seen prices on the internet, but you know how that is. Also, the spring seems a bit messed up, perhaps it got too compressed at one time? Is there a harmless way to take the bottom off so I can take a look at the spring? Does that pin just punch out easily? Also, what value would you put on it? No other marking other than the bottom piece. Thanks in advance.
Dave