I had the same problem but wasn't doing a large transaction. I ended up using Virwox, get linden dollars then transfer from linden to Bitcoin. Fees are horrible, much better off using tradehill and ACH through dwolla.

If you do use Virwox be warned you can only purchase whole dollar amounts and whole bitcoins not fractions. And if you use a credit card be prepared to wait 48 hours to withdraw your bitcoins. You can place the withdrawal immediately but they don't process them for 48 hours.