I found 3 Remington 1100 in my area for just under $500.00. One fixed full choke, One with fixed mod choke and one with a poly choke.
The full choke and poly choke ones handled 3" shells the mod choke one only 2 3/4 .
They have a good reputation for a auto loader. Price is in your range too. You can help your shoulder by getting a shooting vest with shoulder pockets you can install gel pads in. My wife uses such a vest with the middle weight gel pad to keep from bruising her shoulder.
Similar to these but wife's is a Remington brand name and not so costly. she wears a light weight blaze orange over it.

http://www.nicashooting.com/browning...ing-vest-sand/

http://www.nicashooting.com/beretta-...ec-recoil-pad/

Al