ING Sharebuilder - $50 bonus and free trades for a week

I got this in my email for having a ING account. You be the judge if its a good deal. IMHO, its a tad better since they are giving $50 and free trades (up to 50) for a week.

www.sharebuilder.com/em/tradefree
CODE: TRADEFREE

Get $50 PLUS Free Trades for a Week

Since you're a Saver, there's probably an Investor in you, too. Here's a great reason to get started: a $50 bonus and a week of free trading (up to 50 trades) when you invest with ShareBuilder, from ING DIRECT.
With a ShareBuilder account, you can:
Instantly transfer money to and from your Orange Savings AccountSM, Electric OrangeSM and ShareBuilder.
View bank and investment balances all on one screen.
Invest in stocks and ETFs with no minimums.
How to redeem this special offer:
Visit sharebuilder.com/em/tradefree and open a ShareBuilder account using promo code TRADEFREE by October 20, 2009.
TRADE for FREE (up to 50 trades) during the week of October 26-30
(Free trades apply to real-time market order AND Automatic Investment commissions).
You'll see your $50 bonus in your ShareBuilder account 45 days after your first trade.
This limited-time offer is only available to current ING DIRECT Customers without a ShareBuilder account and is a great value. 50 Real-time trades at the standard commission price of $9.95 would cost almost $500. So there's no better time to start investing in your financial future.
Get started now at sharebuilder.com/em/tradefree
Nobody likes fine print. So here's some further detail.
Education Savings, Individual Retirement Accounts, Mutual Funds and Options contracts don't qualify.
Additional services and charges beyond base commissions, such as large order surcharge, express funding and Regulatory Transaction Fee are not covered. Visit the ShareBuilder website for complete pricing & rates.
Automatic Investments must be set up by Monday, October 26, 5PM ET, to receive commission-free trades.

Got the same email.... too bad they don't do OPTIONS!

Can anyone spot any potential flaws in the following plan?

Open ShareBuilder account with bonus code above.
Fund with $50.
On October 26th (first day of free trades), place free trade for a relatively stable ETF (such as the iShares Barclay's 1-3 Year Treasury ETF)
On October 30th (last day of free trades) sell ETF for ~$50
~November 11th receive $50 bonus, cash out ~$100

I opened an account yesterday and didn't see any notice about a credit inquiry. I'll post here if one shows up.

EDIT: Just called, no credit inquiry unless you're opening a margin account.

Tran,

I got the same email, but I believe you have to make a purchase first.