The provided source material does not contain information regarding free samples, promotional offers, no-cost product trials, brand freebies, or mail-in sample programs related to Gumtree. The available data focuses on Gumtree's operational history, job posting services, app development costs, and unrelated local news. Consequently, a detailed article about "Gumtree freebies" cannot be generated based on the provided documents.
Conclusion
No relevant information regarding freebies or samples was found in the provided source material.