Interesting reading and I don't have much to add, but I suggest you find a local laptop 'repairperson' and partner with them... that is, provide them with all your laptop repairs and they give you a reduced price and quick turnaround. Some techs are eager to get the extra business. I'm talking about the DC jack replacements, motherboard testing and replacements. They can be time-consuming when you are not equipped and trained in that field. Hopefully that would leave you available to use your time doing better paying jobs.
Also, on that some note, if you aren't busy enough, find someone who is overwhelmed with work and give them a better hourly rate for taking on some of the overflow. To do this you need to be very good at IT Services.
By the way, the city I live in here in California, actually has some additional requirements if you plan on doing soldering.
Hope this is of some help to you since it is a bit off-topic.