well, price is a sum, agreed between both buyer and seller. I just told my offer. Someone else probably would be happy to get it for 50, I don't know. My price is based on usability of what I'm after. This sets are discussed to death - there are people liking them as original accessories, and some better using camera with really wide and tele lenses.
So it's your decision what you expect - new toy for rare use, or practical tools to get wider or narrower "lenses". Keep in mind that this attachments offer very little if you need wide lens or tele lens.