Even at $50 USD it doesn't make sense to buy these except for the novelty. If you use the calculator below, you'll see that you will never even break even. According to this calculator you are going to have to get a device that has more hashing power or get these for less than $10 USD. I'm scared the fever over ASICs will get folks in so upside down that they'll get a sour taste for BTC and bail on the currency altogether....seen it happen before.
http://mining.thegenesisblock.com/This calculator makes a lot of assumptions about difficulty. It may be that these don't end up making a profit. And that would suck. But the calculator shows some difficulty jumps that I am not sure are realistic. Adjusting the difficulty % increase gives you different results. With the default difficulty % increase on this calculator, the only thing that's profitable is KnC miner, so all Avalon chips are worthless. If that's the case, no one will buy them and hashpower won't increase! Yay!
Seriously though, everyone knows it's a risk. For me, as long as I get close to breaking even I see it as the most anonymous way to accumulate bitcoin. If I have to pay a small % overage for the privilege, it's still worth it to avoid exchanges.
