I use a Mcmurdo Fastfind plus EPIRB. It's a manual activation, handheld unit within built in GPS and 406/121MHz.
As you say £500 sounds a bit steep but you only need to use it once. It's small enough to carry on your person and I use mine whenever I'm ribbing or kayaking. In fact I've just bought a pressurised case so I can take it diving with me. (A dive trip out I was on out to Mexico a couple of years ago managed to misplace a diver and took a good hour to find him, nearly 2 miles away !)
Got mine from Sartech (www.sartech.co.uk
) and they give a 10yr guarantee on the unit.
I believe the current locate time is within 1 hr but this is expected to drop to 'near instantaneous' when the new GEOSAR satellites come on line.
Useful link http://www.cospas-sarsat.org/Index_Frame_English.html
Hope this helps,