“$50 and I'll give you your money back if you write every day for 30 days so everyone who came in put $50 into a PayPal pot and I said I'll donate the rest whatever we end up”

Launch with refundable accountability money

If you lack the credibility to charge for v1, use refundable accountability money instead of a real price. Collect $50 into a pot, refund anyone who completes the challenge, donate the rest. You get a real filter for serious participants without claiming to be a guru, and you validate demand with actual dollars on the table.