Yamaha 473 has this feature and you may get it for around 30K. I too had researched about this feature as one of the 'must haves' while finalizing my AVR, but till date have not used it!
My Tatasky is connected to the TV via HDMI and to the AVR via an optical cable. This would give me regular stereo sound via HDMI while watching standard programming without the AVR being swiched on. If the AVR is switched on, I can get the 5.1 sound on HD channels via the optical through the AVR. I've never come across a scenario where I have had to keep the AVR switched on for regular tv watching.