I've got 11 sysadmins working for me at the moment. Salary ranges from 50K to 130K. Your salary will depend on these things:
3. your technical experience
4. your ability to communicate
SAs on the coasts tend to make more, .EDU pay is low, some industries (like financial services, pharma or video games) will likely pay more. Experience in "big environments" with tech where there aren't a lot of people who know it will help. If you can communicate, you're worth more than someone your boss has to hide from the customers :-)
The "hot" experience varies from time to time, but right now people who can handle "big storage", and DR seem to be hotter than some others. NOC staff are pretty easy to find.
When I'm looking for a more junior person, my *biggest* questions are things like "Can I give this person a reasonable problem to solve and turn them loose to solve it mostly by themselves? Will they expect me or more senior people to lead them through it, or will they work at figuring it out and only ask for help when they need it?"
For a more senior person, my *biggest* questions are more like "can this person not only solve the problems we know about, but can they figure out which problems we should be solving?"
Beginner, mid-level or senior, being a self-starter is a massive plus.