At that temperature range you are somewhat limited to thermocouple or RTD sensors. Neither sensor is especially expensive but the proper electronic interfacing is somewhat complex and not cheap. I prefer RTD sensors for their better accuracy. For either sensor the temperature range is dictated by the type of insulation used for the specific sensor obtained, thermocouples are really a +/- 5 degree device especially at elevated temperatures. A thermocouple in theory can read to around 2000 F, but most won't because of the actual wire insulation used, so you should make sure whatever specific sensor, TC or RTD, you select is rated higher then the max temperature it will see in your specific application.