It's just further evidence that the people who buy and sell second hand stuff are catching on to the idea that old tools can be valuable. With no idea on the detail of which tools are valuable and which aren't, it's worth a punt at a high price to see if anyone bites. You can always drop the price until someone does.
I was flicking through one of those picture book guides to making money at car boot sales the other day - in a s/h shop naturally - and was quite pleased to see that although it did have sections on old toys, jewellery, china, glassware, 60s memorabilia, football programmes and so on, there was NO mention of tools at all. The longer they stay disregarded the better, in my opinion as a buyer.
But I guess we are all to blame for increasing interest, wittering on about the things where Google will find us!