Good ones are the Canon EOS 350D, and the Nikon D50.
With the Nikon you need to multiply focal lenghts with 1.5, with the Canon you need to multiply focal lenghts with 1.6.
For both, if you are looking for just one lens, the Sigma 18-125mm is a good, affordable choice. For the Canon you can also choose the kit lens (18-55mm) and get the EF 28-105mm f3.5-4.5 II USM, a sharp, good lens for not too much. This all should keep you within 600pounds
Canon EOS 350D, Tamron SP AF 90mm F/2.8 macro, Sigma 18-50mm F2.8 DC EX, Canon EF 70-200mm f/4 L USM, Tokina AT-X124 Pro 12-24mm F4, Soligor 1.7x C/D4 DG Teleconvertor, Manfrotto 724B tripod, Canon Powershot S30