At that point, just buy a Jalapeno.
The only way it *might* be worth it is if you were to avoid buying a Jalapeno. They're great for just getting into mining, but they're the least cost-effective ASICs out there.
$600 gets you 4 Jalapenos, which is ~18GH/s. $650 gets you 1 Little Single, which is ~30GH/s. Worth the extra $50!
They're only worth it if you've got less than a few hundred USD to spend, and you're only buying 1-2 to try this whole mining thing out.