Facebook lead costs for local services commonly land anywhere from a few dollars (broad consumer offers, instant forms) to $30–$80+ (considered purchases, landing-page flows). The spread is so wide that published averages mislead. Your break-even math is the only benchmark that matters: cost per lead × leads-per-customer must sit under margin per customer.
Budget-wise, give the algorithm enough to learn: roughly 50 conversion events per week per ad set is Meta's own learning-phase guidance, which at a $10 lead means ~$70/day during testing. Starving campaigns at $5/day mostly buys noise.
Judge it against your Google numbers after 30 days on the same landing math. For 'my pipe burst' businesses, search usually wins; for offers people didn't know to want, Facebook earns its seat.