I think the cheapest you're going to find is called "GetDataBack" from http://www.runtime.org
It comes in FAT32 and NTFS formats. Check to see what you drive is formatted in before ordering.
It's about $70, but it's saved me on several occasions and does a really good job, so long as you haven't made too many changes to your hard drive recently. Any time you add files or software, you run the risk of over-writing recoverable data. You should also plan on having a separate drive to recover the data to.