Those are the prices from when they were selling the NOS and buybacks. This is how they stayed in business through the court rulings. They couldn't import new stock so they were selling what they had warehoused pre-ban and what they could buyback from previous customers.
The 2017 prices are published (I'm guessing the ban doesn't end immediately) and they are indeed 10% cheaper.
[edit] I'm not affiliated with zen magnets in any way, but I bought their largest set available pre-ban and have been following their progress on this ever since. They are an extremely reputable company and I highly recommend them.