I responsded to another thread ...on same issue ...
but a few months ago, I found a Browning Citori, Lightning model, 28" barrels, 12ga - and it had the old style Invector screw in chokes for around $ 750. It had a few nicks in the stock ...but I'll sand those out and refinish it when I have time ... New that gun is retailing for around $ 1,750 these days. In 1988, I bought myself one - and paid about $ 750 for it new ( and still have it ). Its not the Citori model I shoot myself these days / because I realize it never fit me right ( too much drop at comb ) - so I shoot the Browning Citori XS Skeet models, with 30" barrels and an adjustable comb for hunting birds, Skeet and Sporting clays .....
But it was a good buy for a good used gun / that I'll clean up and put away for one of my 10 grandkids ...someday ...
http://www.browning.com/products/catalog/firearms/detail.asp?value=008B&cat_id=013&type_id=461
This is the gun I shoot myself ...because it fits better / and I recommend it because it will fit a lot of shooters right out of the box because of the adj comb. Looking for a used XS Skeet is a good plan too / but new they are around $3,000 now - and used about $ 2,000 - $2,500 now ...but a great option, in my opinion.
http://www.browning.com/products/catalog/firearms/detail.asp?value=008B&cat_id=013&type_id=066
I like the XS Skeet model so much --- I bought them in 12, 20, 28ga and .410 ...
http://thefiringline.com/forums/attachment.php?attachmentid=52948&d=1256245028
There are a lot of good used guns out there ...and buying used will always save you some money / but try and get a buddy or a mentor to help you out and wade thru the stuff you don't want ...and find a good one.
Beretta makes good solid guns / I don't own them because they don't "fit" me. In general, you will find if a Browning fits you / a Beretta will not --- an vice versa ... Don't let me, or anyone else, overinfluence you on one brand of gun ....we all shoot what fits us personally / buy what we think is the strongest guns ( for me that is Browning ) ... I'm 6'5" and 290 lbs with big hands ...and I like heavier / high comb guns ....
Rugers are not bad guns / but their quality has gone down in recent years. An older one might be a great find. I would also stay away from guns that don't have screw in chokes(regardless of who made them). You can add them - but its usually more than you want to spend to have it done right ...and if its done wrong ...the barrels are ruined. New barrels will often cost you more than a new gun...
Good luck / and no matter what --- have fun with the search.
Go to your local club / rent some guns if you can .....and talk to guys / ask them what they bought, why, would they buy it again. Many guys will help you out / maybe let you put some shells thru one of their guns. Most of us that are into Target shooting - have 20 or 30 shotguns ... and bringing something out for a guy to try is not a big deal. I have a number of guns I keep around to help train new shooters, kids, grandkids, etc ( I never sell anything ..) ...