Lenovo has a price protection plan. If the price drops within 21 days (pretty sure it's 21; could be a month but either way you're covered) of your order you get the difference refunded. In order to get the refund configure the exact
same machine you did before, down to the model number, warranty and everything, and instead of clicking "buy now", click "save order as quote". Call up Lenovo, and tell them about the price drop. They'll ask for your quote, give them the 6-digit (I believe; it's been almost a year since I did this) quote number, and you get the refund in 10 business days or so. I got a refund when that happened to me; consult this thread.
Edit: I should mention that you can do this once
per system. If you get a refund and the price drops again, unlikely as it may be, you won't be eligible for a second refund.