Are there any plug in (or even wired in) timers which allow one to
turn something on for an hour or so and then turn off automatically?

I'm after something like the immersion heater 'booster' switches that
allow you to press a button to turn the immersion heater on for an
hour but then revert to normal timed operation. I really want a plug
in version though for controlling 1kW or so and I want it at a
reasonable price, not the 20 pounds or more that the immersion heater
switches cost.

Any suggestions?

--
Chris Green