buds has them for 592
For that matter Adventure Outdoors has nearly always been the cheapest local option for anything Glock.GA firing line has them listed at $585 on their gallery of guns page. Will likely be a few dollars cheaper on the shelf.
Out of stock, and what did they do with the third magazine? That's thirty bucks all by itself. The photo is not a Gen 4, even though it says it is a Gen 4. Weird.