I do about 5 calls a month. Mostly just software related. When it comes to major hardware failure there's only so much I can do.
I'm the only Mac "repairman" in a 20 mile radius and I'm very cheap. I usually charge about $45/hr for my services. Comparable Windows service in my area will run $85/hr.
The other question is, freelance or authorized Apple Warranty.
To become an authorized Apple service location takes a bunch of certification, but more importantly, affiliation with an authorized dealer, which has ungawdly difficult financial and qualification requirements. Don't know what it is now, but at one point you had to commit to buying something like $100,000 worth of spare parts to keep in stock.
IIRC Apple pays a flat rate on warranty repairs (no matter how long it takes to do the repair), and it's not generous.
Obviously, the freelancer cannot do Apple Warranty work.