Yep, I got snagged on it too. I ordered a new Slick mag for my non-impulse side from Spruce and waited a week to order the Surefly for the impulse side because I knew I'd need some additional parts and I could get free shipping on the parts when I ordered the Surefly.
The next week, boom - $200 increase. I briefly looked around but it seems that only Spruce and Surefly sell the units, so just chalked it up to Aviation Inflation.