I've used AmmoSeek.com a few times when I was on the hunt for some .223 and 9mm ammo during a shortage last year. Overall, I found it pretty handy for comparing prices across different retailers. Most of the listings were accurate, but I did notice that a couple of prices fluctuated quite a bit since the site pulls from various sellers. What I did was double-check a couple of the retailers before hitting 'buy' to make sure they were reputable, and I've avoided any sketchy sellers so far. Just be wary of shipping costs because sometimes they can add up and make a good deal not so great. But for finding ammo, I'd say give it a shot—just keep your eyes peeled on those seller ratings.