It is a very good deal and obviously a method to attract customers since you will get lots of mailings once you place an order. For example, I just received a year end mailing from Mystic offering the latest supplement. 2016 issues, etc. Mystic also does not over price the supplements.
With the vinyl sealed seams on the edges they do look a bit cheap but then I have 28 Mystic binders and a few slip cases. I picked up many of mine from fellow collectors migrating and off eBay
The binders are not bad and seem to be fairly durable. The primary issue I have had with binders is the rings getting out of whack so they are misaligned and do not close. The Mystic have done better than binders so what I paid, I am happy.
However, you can buy binders at any price/quality level you want. I have many different ones.
You will need more since once you put stamps on the pages they will not fit in the 3 binders provided.