This deal has ended.
Buy.com has the Kingston 4GB DataTraveler USB Flash Drive for just $14.95, the lowest price to-date. It's well reviewed, having received 4.5 out of 5 stars from 33 buyers. If you sign up for and pay via Google Checkout through 6/30, you can take an additional $10 off the price. Shipping is free and there is no sales tax (except CA, MA, MD, TN).