We carry all our software tools on a 500 gb passport and we use it to backup files for a reload.
Our on site rate is $120 for business or homes out of town, $100 for homes in town charging one way travel up to about 10 minutes I can get anywhere in town.
I will go onsite determine what the problem is and how much time it takes to fix it. I advise the client that it will take 2 or 3 hrs and will offer to fix it in his home for the $100 per hour or take it back to the shop for $59.99 per hour plus the pickup and drop off fee or let him pick it up from the store when we are done. I have stayed on site up to about 4 hrs and got paid $400 plus tax to do a complete backup, reinstallation (OEM), download drivers, install clients software and printers/cameras and antivirus then run the scan on the backup on my passport before reloading it to their clean machine. This is the exception and it is only in those cases where the client insists the machine not leave their home and they have pretty big backup that takes some time.
On the other side, I have done a complete restore and setup in under 1 hr using F11 when the backup is small and everything just clicks. That would be cheaper than if I took it back to the shop. Our shop rates are standardized meaning we charge 1 hr backup, 2 hrs reload, 1 hr security and updates so it would be about $239.96 for the same thing in the shop plus $20 pickup fee.
Your other question....how long do I fool with a machine before I wipe and reload, not long. If I cannot see that it is going my way the first 30 minutes then its time to switch plans. Sometimes I get sucked into putting too much time in before switching to reload but not too often.
I tell my techs if you don't know exactly what the problem is within 10 minutes then call the senior tech, manager or me... This was when I was hiring A+ grads from tech schools...