I think this depends on what exactly you want the carabiners for. Most hardware stores carry a variety of carabiners in a range of sizes, weights, and purposes. The "S-Biner", for example, is a cheap, stainless steel multi-purpose clip. I use them for all sorts of household things and while camping, but there aren't really any ways to use them climbing. You'll also find bigger, multipurpose biners like [this one], but this type is only good to about 150 pounds. There are also biners that are very much like what climbers use (though generally heavier and stronger), such as this one.
On the other hand, climbing biners are generally specific to the needs of climbers (light weight, very strong up to certain loads, specific diameters at top and bottom, wire gate, bent gate, keylock, etc.). Depending on your needs they might suit you well. A pack of six Black Diamond Neutrino biners is only $35, so if you want something that takes big loads and is still small and lightweight (and colorful!), go for it. Your best source for these types of biners would be climbers retiring their gear. Most climbers won't use gear after it has a certain amount of use, so they are often getting rid of well-used biners that aren't safe for climbing anymore.
So how do you know a good quality carabiner? Any biner from the major climbing manufacturers (Black Diamond, Mammut, Omega Pacific, CAMP, Petzl - really ) will be more than enough biner for day-to-day uses. REI offers a good variety. A couple of things to note, aside from price, are the strength (almost all hardware has a strength rating stamped into it - it is often in kilonewtons [kN] or safe working load [SWL] in pounds), the size, the width of the opening, the action of the opening (is it sticky? difficult? smooth?), and the material. Most standard climbing biners are made of aluminum, for example, which doesn't mesh well with steel (so, an aluminum biner used on steel cable is bad for the biner).