IK Multimedia has announced it has extended the SampleTank for iOS special sale until May 31st, 2012.
You can get SampleTank for iOS for $9.99 / €7.99 (normally $19.99 / €15.99) in the App Store, and the All Sounds pack, which includes an additional 400 sounds, for $19.99 / €15.99 (normally $39.99 / €31.99) through in-app purchase. If you are looking to add more sounds to your existing SampleTank Free app you can get 50% off the Upgrade to SampleTank and the All Sounds pack through in-app purchase as well.