If you keep an eyeball on them at ebay, they seem to be selling in the $70 - $120 range, more or less, depending on type and condition. They sell for less here, as you may know.
I buy them just because I like 'em. I don't think they are much of a long-term investment because eventually something will come along thats smaller and brighter and better, but you never know.
Part of the equation is that their numbers are limited. As soon as Peak announced that it was ending production of its multi-LED lights, I had to have one (and got one). Five minutes earlier, I couldn't have cared less.
best regards