Often with beauty it can be hard to justify spending so much on something when there is a dupe. It costs around £18 for what is the best blending brush around, but it's a hell of a lot of money and not everyone can afford to pay that price tag for a brush. This little gem is from eBay and cost my 99p, that was including delivery. You would think it wouldn't be of any good use being so cheap, but it's actually really lovely.
The brush shape is very similar to the 217 so it makes it easy to control where you need to blend. The bristles are soft, maybe slightly scratchy but nothing major. I really enjoy wearing eyeshadow so I decided to buy two just so I have a backup. In terms of how they wash they also wash really well considering the price, I would recommend trying not to get water around the mental outer as this could make it come loose, but other than that there was no shedding and no change in quality.
If you are looking to be more experimental with eyeshadow then a blending brush is a really good place to start, and at this price you can't really beat it. To find this brush on eBay just type in "eyeshadow brush 217." There is no reference to MAC.