I would go with the Remington 870 Express combo, 1 20" barrel with an improved cylinder for HD and deer hunting, and 1 28" barrel for birds, skeet and other such sports, the 28" comes with the modified choke but can be easily changed out with other chokes.
The shotgun should be under $400.00.
You can also get the 870 upgrade kit which comes with 2 chokes IC and Full and a choke tube speed wrench also a 1 oz. bottle of Rem oil. I got the uprade kit at Wal-Mart for $30.00.
All things said you will have a gun that will out live you..
Just ask Dave he's got 870's that are older than me