This is the thing about working for free, or cheap, because you "want the experience"
The first thing you have to ask is: What experience am I about to get?
If someone is proposing that you work an unpaid internship because you'll get a lot of experience, then you have to make sure that you're actually working at a place that is actually capable (and willing) to teach you something you need to know . . . the more specfic, the better.
If someone wants you to perform in an artistic event, "for the exposure", then I think you are obligated to find what that means:
Does it mean that press will be on hand to review the show?
Does it mean that you'll have a chance to work with great fellow artists in a positive work environment?
Does it mean that important members of your industry will be in the audience to see the work?
Or does it just mean that you're working for free and the most you'll get out the engagement is a credit on a back of your resume?
There's no shame in being an unpaid intern, or volunteering your artistic talents. It can be a great way to build your career.
But I also think it's worth pointing out that some arts organizations have built their entire business model around taking a lot from people and giving little in return.
Whether somebody is paying you or not, you're still entering into a relationship with them.
You know the relationship works for them.
Make sure it works for you.