I’m pretty sure they did a couple runs of them early on, with each selling out quickly. I bought three after waiting several months for the email notification that they were back in stock. I believe they were already out and in use by other people by the time they restocked and I ordered mine.
I just received my first Circle 10 today, partly because I just wanted to have one, but also to compare it to my Toth mags. The Toth mag looks like a slightly “cleaned up” version of the Circle 10. My understanding is that they used a more modern plastic to add strength, while eliminating the steel reinforcement on the front that the Circle 10 has, so it will be interesting to see how they both hold up in the long run. I don’t plan to torture test them or anything, just use them regularly. I like the idea of supporting a US-made product if they could only keep them in stock.