Adding New Wiring and Switches:
When you hire an electrician, even for a small job like installing a light switch, be aware that most charge a minimum fee for a visit. But that fee will roll into the cost of the job. In other words, although an electrician may charge $50 just to walk in the door, that money might cover the first hour of work. The cost of the job will vary depending on the complexity and parts needed. One factor that often contributes to a job's complexity is access. How difficult will it be to run wires, etc.? Will your electrician need to cut into the walls, and if so, how much? Also that issue of capacity may arise when you add new wiring or install switches. A cheap and simple job can get expensive when you need to update or change your electrical board.
Installing Lighting Fixture:
If the cost to install a light fixture seems high, that's because it includes the price of the fixture. Here's one of the few electrical jobs that may end up costing you more in materials than labor. But again, capacity issues that require board upgrades or access complications may raise those labor costs. Your electrician should be able to give you an estimate before starting the job.