Step 4: Pricing
An interesting aside about having a sliding scale policy: I've found that very few people have asked to pay less than half of our stated weekly price. Even though we say "We work with all families regardless of their ability to pay" in our brochures, only about 1-2% of all people interested in camp have asked to pay less than half our listed price. My interpretation is that families that can only afford $0 - 50 /week don't expect our price to come down enough, and would rather ask for financial assistance from a camp with a lower full price. This has meant that we end up getting most of our families in this price range through direct outreach, where we have control over how much outreach we do. The upshot of this is that we haven't been flooded by requests to come to camp for free (we hardly get any), and so having this policy didn't put us under any unexpectedly large financial strain. Or, really, under any strain at all.
It also means that we have to work harder to actually attract an economically diverse population. There are lots of pretty friendly organizations in any city that can help you get in contact with families outside of the middle-class that typically looks for (and can afford) "enrichment" programs.
In Boston/Cambridge, we found that parents could get childcare vouchers from the city. Getting on the list of organizations that could accept these vouchers was incredibly helpful. In Cambridge the people to talk to for this are the Childcare Resource Center. Other cities and states probably have similar organizations.