I recently purchased a 10 outlet APC surge protector from Circuit City for about $30. It has a decent supression/joule rating (around 1800 I believe) as well as EMI/RFI filtering and spots for coax cable & phone line. It was designed for use with a computer system, but it works just fine for me.
The true test for these sort of things, IMO, is when you actually have a surge or strike and whether the unit protects your equipment.
What blows my mind with the snake oil power conditioning stuff is that a computer is SO much more sensitive to power stability issues than most consumer-grade electronics yet power conditioning/supply components (UPS, surge protectors, etc.) are SO much cheaper than the stuff they sell for HT applications. Look at the UPS/surge protector connected to your computer at work...it probably didn't cost more than $50 yet it is protecting a >$1000 piece of equipment (for me anyway) with many more thousands worth of data stored on it.
My thought is: good enough for a PC, good enough for AV.