Me! I do this all the time. Most recently I picked up this mannequin arm from Reverse Garbage when I popped out to the farmer's markets looking for ingredients for dinner that night. I took a detour thinking "I'll just have a peek but I won't buy anything. Just browse." Woops.
Reverse Garbage is a not-for-profit cooperative which recycles items that would otherwise end up at the landfill and they always have the most curious of things for sale. Last weekend it was full of mannequin pieces - busts, heads, legs, arms, torsos. You can see more on my Flickr photostream. It was eerie but I couldn't resist and I raised a few eyebrows carrying this arm through the markets. But I think it is beautiful.
So I have to ask, what is the strangest / coolest thing you have bought?