I suggest holding out for something that can be upgraded. Any rifle can be upgraded, but aftermarket support for Mossberg is virtually nil. Barrels, stocks, triggers....
That said, if you dig that rifle and it's what your budget will allow, go for it. Enjoy it and learn everything you can with it.
Good luck
FYI, a Stevens 200 can be had within the same budget, it's a lower priced Savage just waiting for upgrades.
I seem to recall reading that the nightrain was very good value for the money, of course all of you fellows have shot the mossberg before and are giving this fellow your view points from having shot the mossberg rifle right?
Do you know if this is the II model
If the guy has $500 to spend on an accurate piece that is scoped and ready to go he she be encouraged to do so. IMHO. FS