I'll second/third/fourth/fifth the Browning (Miroku) BSS boxlock recommendation. Modern gun, modern steel, modern dimensions, heavy enough for clays, right in your price range, available with PG or straight grip. At 5'7", you may prefer the 28" barrels. That would save some money and be easier to find than the 30" version (also, the 30" was available only in the PG configuration). If you prefer double triggers, look for the Miroku or Charles Daly (Miroku) 500, generally with double triggers and a splinter f/e, somewhat lighter barrel profile. You can often find a very sweet Miroku/Daly 500 for well under $1K.
Another option would be the SKB 100/200 series. I love Spanish guns, but there are very few that I would use for volume clays shooting. In the American classics, Fox Sterlingworth would be the choice, followed by a Parker VH or Trojan. If you want an American sidelock, the Smith Ideal is way better looking than a Field gun, but watch out for stock cracks behind the locks if you are going to use it a lot with promo loads. The BSS, SKB, Sterlingworth, and VH/Trojan will eat just about any reasonable target loads you would want to feed them. There are lots of light factory target loads out there, but I like the Fiocchi 7/8 oz training loads.
