Disk Drill is available in a Free/Basic version and a Pro version for $89.
Disk Drill is a Mac data recovery software designed natively for Mac OS: easily protect your files from accidental deletion with Recovery Vault and recover lost data from Mac disks. When something is deleted Recovery Vault makes it possible to recover not only the file itself, but also its properties, such as original file name, location, etc. So you will always be able to recover data from Mac files system (HFS/HFS+) and FAT32 partitions. Disk Drill also includes more...
- improved data recovery on disk images
- many speed and stability improvements
- improved data protection when Mac awakes from sleep and idle modes
- improved attaching of disk images with corrupted data structures
- correct enumeration of files in disk/partition info
- updated internal disk reading libs
- OS X 10.6.8 or later