OK so there is a fine line here. First off - data recovery is not cheap. And there is a reason for this. I recently did a 12.9 GB maxtor drive. This drive suffered from a failed head stack. We needed four donor drives to get all the parts we needed to rebuild the damaged drive and spent almost 5 hours till we got the drive rebuilt and recognized on the Deepspar imager. We then ran it round the clock on the imager from Monday afternoon till Friday afternoon and got a bit less than 97% of the surface imaged. The file structure was toast, so we ran XWays forensic software to scan and do the logical file recovery.
The problem is when the 'local computer shop' does data recovery. They probably run the same software you can buy for less than 100 bucks against the drive and call it recovered. This stuff is great if you have a functioning drive, but won't handle bad sectors like dedicated hardware imaging devices do (For example, the deepspar forensic edition imager is close to $5000). $300 for a recovery is CHEAP!
Also most people want to know what it is going to cost them before they send their drive for recovery, so the DR industry has come up with the 'fixed price senario'. Two ways to do that. Assume that some jobs you will lose money, some you will make money and go for an average. The other is to set your price, and only go to a certain level. Drives beyond that level are called unrecoverable. The average local computer shop probably doesn't do enough high end recoveries to justify the cost of clean room, tools, and the reasearch that goes into a physical recovery, or even the expense of the more difficult logical recoveries ( SA area or firmware corruption, bad translator table, bad p-list or g-list.)
You can also run into parts issues. I have a 60 GB 2.5 in Hitachi drive with a bad logic board sitting on the bench. I'm still looking for a compatible donor drive. While I have 7 of these same drives in stock - none of them look to be a good match. I've found 2 matching drives from a vendor, at a cost of $180.00 each. Why? They know it is for a data recovery because I had multiple identificatin numbers on the drive that had to match. Normally a board swap is a pretty easy recovery, assuming no other dmage has occurred to internal components. I was able to get the drive to spin up with one of the boars I have, but untill I ge the correct board, I can't even be 100% certain the spindle motor is good. If the board failed while the drive was running, then there is a potential there was head or platter damage, but again, until I have a running drive, I can't be certain. Now since this drive is for my boss's cousin, it is not a high priority job, I can look further for the parts. But if it was for a customer who needed their data ASAP, then I would have pretty much had to go for the $180 dollar drives, and they were still not exact matches.
Hopefully this explains a bit why recovery can be such an expensive proposition. Regular backups of your data is a WHOLE heck of a lot cheaper!