Referrals are the cheapest and the slowest. They arrive when they arrive. Your own marketing puts you in control and also puts you in charge of the ads, the landing pages, the follow up and the verification, which is a second job on top of broking.
Buying leads trades money for time. You agree what a lead is and what one costs, and records arrive in your CRM. The catch is that the word lead covers everything from a shared list to a verified, finance screened enquiry. Before you buy, read what an exclusive mortgage lead should cover and ask any supplier the questions on that page.