I've used AmmoSeek a few times when I was trying to find some 9mm and .223 ammo. It's pretty handy since it aggregates prices from various sellers, which can save you a lot of time compared to visiting each site individually. The prices were decent, usually better than my local shops, but I did notice some better deals might be stocked out or were just bait-and-switches, so pay attention to those listings. Always check reviews for the sellers if you're unfamiliar with them; some are great, but a couple didn't have the best reputations. Overall, I think it's legit, just be cautious, and don't rush into buying without doing a bit of homework on the seller.