The cost will be $1,650! I was hoping it would be more like $500-800. Apparently the drive has a serious internal fault. The recovery result will depend on how good an image they get after making temporary repairs. There is no guarantee. However, from previous experience they feel the prognosis is good. Fortunately the fee is only payable if they successfully recover the data.
Unfortunately the data was not backed up as I thought (you also would expect a new machine to do this). Given the cost I'm now facing, I intend to approach Apple to discuss whether they are able to subsidise this cost––considering the fault was not mine. I'm sure the "back up" issue will be a potential exit strategy for them.
If the laptop didn't have key documents relating to Maria's funeral (especially one that I typed during her last night and no longer have a hard- or soft-copy on hand), I would let it slide. Whether or not Apple come to the party, won't stop me from proceeding with the recovery.
