There are only two rifles to consider in your price range the Air Arms TX200 or the Weihrauch HW77 both are well made and very acurate I would favour the TX200 it has less recoil and is in my opinion a nicer rifle to shoot and to look at,if you can get either one with a V MACH tuning kit fitted it would be even better,both of these rifles you will find for sale on Gunstar at around £250 to £300 a V Mach tuning kit would cost you new about £70 but is well worth it and would greatly improve the rifles performance.Good Luck.
Regards Ken.