It all depends upon the purpose intended.
Assuming it is mostly for coins and jewelry, I'd look at the following models/brands
New..
Teknetics Euro pro – light, really easy to swing and a fast processor. I think this machine is a fantastic value and it punches above its class.
Tesro Compadre – light, really easy to swing and a very fast processor. This is almost a must-have machine. It loves coins and jewelry.
Tesoro silver umax – I've not used one. The machine is very popular though.
Fisher F2 – I've not used one. It is likely to be one of the more popular entry level machines though and it seems as though its users love them.
Whites Treasure Master – I have not used one. It seems to be a fairly popular machine and its users seem to like the machine quite a lot.
Used..
Fisher F4 – light and easy to swing. It is a very capable machine
Tesoro Cibola – I haven't used one, but they're very popular machines. Richard (Backwoodsmetaldetectors) has one (new in box) at the price point you're looking at. Give him a call (or email) to see if he still has it.
I'm sure that I missed mentioning other capable machines, but these were the machines that I first thought of with your given criteria.