If it's a legitimate retailer, they're doing a bad job at making it seem so.
I've purchased games from foreign key sellers before with no issue - sites that at least make an effort to explain how the system works, where they get their keys from, and how they're able to sell them cheaply.
On this site though, if you go to their 'About' section, it's just some bullshit saying "We're virtual gaming service provider. We offer PC game CD-Keys, MMORPGs, such as World of Warcraft, Star Wars: The Old Republic - SWTOR, Call of Duty Modern Warfare 3, FIFA 12..."
Also in their FAQ:
Q: Why are your CD Keys and Time Cards so cheap?
A: Since we always have huge amount of products in the inventory and we sell so many of them each day, so we can offer competitive prices in the market.
Yeah, whatever.
They mention absolutely nothing about where they're from or how they operate.
They also make very little effort to distinguish between Steam keys and regular CD keys. The Darkness II, for example, is a Steam game. Anno 2070 on the other hand, is not. The only way you'd be able to tell is by scrolling to the bottom of the product page where it gives you instructions on how to activate the game.
I'd probably avoid them for now.