Here is a better math. No preorders, buy 3Th worth of S2 for $6.3K or $5.2K if you got coupons TODAY.
Conclusion: most preorders are not worth it.
I'll wait to see what the S3 looks like before I buy any more equipment.
Are you really considering buying more hardware after the datatank announcement?
They are offering $0.93/gh and $0.025/kwh..