I am in the same situation (being a poor college student and all). I have contemplated selling a gun or two for something else. I have learned that I better keep what I got and save for what I want. The reason being, you will never have to worry about getting rid of perfectly good gun that you know and are used to.
In fact what happened to me was funny...I had a MAK-90 in 99% condition and traded that and little $ for a P226 in .357sig. I really do regret the move now, not because of the Sig, but because I had paid almost nothing for the AK and later learned that I should've kept it seeing how it is much better made than the Romanian AKs out there and I probably wont ever find it again for what I originally paid.
Again, keep what you got and save for what you want, unless you never want to shoot the sig ever again or if its a situation where it's simply a matter of not liking the gun. Some people dont like triggers so the gid rid of there guns. Some people dont like how it feels when fired, they lose it. Depends on how much you like the sig or not. I have plenty of guns that I dont shoot as often as other but love them just the same
One gun that I did get rid of for money was the Kel-Tec .380. The thing was just too small and I could never shoot it well....ever. So, i got rid of it.