I had been buying quite a few of these over the last 3 years or so, as well as the other Highlander figures, to make my customs. I can tell you that for the full figure on the box I don't think I ever paid more than $40-$50 shipped (USD). Usually I was able to pick them up in the $30-$40 range.
Obviously there were people on ebay selling for higher -- all the way up to $200, or in some cases way more. However, I never saw those sell (and obviously I didn't buy any of those). I would watch lots of them and see how many of the higher priced ones would end without sales and be relisted, and any that were well over $50 did not seem to sell.
That's simply my observations of course. I only look sporadically now on ebay. From what I see on there now they are way overpriced. They originally sold for about $45, and I think hovering somewhere around there is reasonable. IMHO.