It is generally true when talking about bindings that cheap = fragile, expensive = durable. The less you spend on a binding the more plastic it has in its construction, while the more you spend the more metal it has in its construction.
You should also view a binding as an investment. A binding can be transferred from ski to ski, so when your ski dies or you outgrow it you can take your nice binding off it and mount it on the next ski you buy. So, if you spend a little extra now, you don't need to do it again when you buy your next pair of skis.
If you bought a binding in the 12-DIN category, something like a Salomon STH 12 (with Driver toe), you would have a binding around $200 that would last you a good while.