You should market the patented Phillip O'Hare DIY Data Recovery Kit (tm) A nice shrinkwrapped package consisting of a rubber mallet, security Torx bit and a pair of lint free gloves
I think the hardest part of your plan really is to get started. If you can get a few companies to give you a try then word of mouth should keep you going. A flashy professional looking website would be good as well. I've met loads of people that judge a company based on how nice the website looks.
Once you've done a few drives then you can splash out on a copy of a NTFS/FAT32/ext2 undelete utility.
And you've got no competition from me so don't worry
- Trevor