When I was in the mobile mechanical repair business some years ago, I rarely worked on push mowers because I just told the customers that they would be better off buying a new one.
You would get a job at any OPE dealership in Australia in a snap talking like that!
When it comes to rates, I believe that it really depends on what people in your area will be willing to spend and what you feel your time is worth.
At this stage, I am only doing the odd job for people but if I am rebuilding a saw that will cost a lot to replace, you can make some money. If it is a cheaper low cost saw, as said above, the owner is not likley interested in paying a lot to fix it.
I know the local shops charge you $20 to $30 just th have a look at it, then $80+/hr
As a home repair person you dont have the business overheads like rent and wages to pay so you can charge far less and probably make more than the professional business.
I recently repaired an old Echo for a local bloke. He brought it to me saying it would start on choke but died and would not rev up.
I spent an hour or so cleaning it out a bit, stripped the carb, pulled the jug, popped he muffler off etc etc and could find nothing wrong.
It was not a big money saw so I was conscious not to spend too much time on it.
I ended up pulling the carb limiters and re-tuning it till it ran.
I charged him $60 for my time and told him it was not perfect and may have leaking crank seals that would cost a bit more to fix but I left it to him to decide.
He got back to me and said it goes great and is very happy.
If it was an MS660 used by someone who needed it regularly, I would have changed the seals and charged appropriately as it is a saw worth fixing