Steffen,
There are several around this budget at a new price. Lanber, Sabatti, Lincoln, Bettinsoli, Laurona, Baikal, Verney Carron, and loads more. But. You are better off getting something nearly new from the higher price brackets. I would suggest a searching for a little while to locate a good second hand model from a higher end brand. Beretta 686, to a Miroku, Browning etc. all these in over and under. There are some very good semi-auto's out there too, some which are not too far away from your budget at a new price. A lot will depend on your build, your physical dimensions. All the above have different dimensions to their stocks, some are heavier than others and barrel length varies.
What will you be shooting mostly ???? It sounds like you are rough shooting, if so go for a 28 inch barrel. This will be manoeverable enough to be stable but pointable enough to use. My own preference is for an over and under, you might like a side by side but beware it is easier to use an over and under more effectively. Go to a clay ground and ask about, try a few different ones and see what you like.
The thing is the more people you ask the more answers you will get, and probably more than one from these people too.
If I were to say one, go for that 686, second hand. Look after it and it will last longer than you will.
Hope I did'nt confuse you with my ramblings, it's a daunting choice getting your first. You won't go wrong with Beretta, I have 3 !
Cheers
Ade