Like I had mentioned in my previous post, it's 2 reasons - 1. The fact that exclusives are only available at sideshow. 2. The piece of mind of ordering through sideshow - no cancellation fees, and if there is anything wrong with the product, knowing that their customer service is top notch and they will always take care of you.
And then on top of that, you are getting some points back for your orders that you can use anytime in the future (granted not many)
I've debated many times over what to order from Sideshow vs another retailer. Often times it came down to if there was an exclusive available that I wanted, and how much cheaper it was to get from someone else.