Data Doctor Recovery

I am starting a PC Repair Business. I would like to offer data recovery for people who accidentally deleted files. I assume there is decent software out there for that. What is the best solution for this scenario?
Also, I would like to offer the same for people with dead, or dying, hard drives. This would require a more “physical” approach. What is the best solution for this scenario?
Please answer both questions. I am not sure how much money I want to sink into this… I guess it depends on the market for the service. For the first example, I would have no problem buying software (but freeware is nice too, if it works). For the second example, I will assume it is expensive, so just give me whatever you can.
Top answer will go to whoever give me the most useful info (answers both questions, gives more than one solution to each example, gives me something I can actually use and works). Thank you!