Saiga 12's are great, but don't let anybody blow smoke up yer butt that they're failure-free. Like _all_ semi-auto shotties, they can be VERY particular about what will properly feed and cycle. I've shot in 3 USPSA shotgun matches with my Saiga and STILL haven't found the right "tuning" (ammo + gas adjust). To top it off, changing mags quickly is a bear, just like standard AKs (worse, actually).
I love my Saiga, and the price listed on that website is good, but don't buy into any hype that makes it seem like they're completely reliable.