Blockchain technology has pioneered a new consensus approach to building a distributed public ledger globally. A key feature expected from cryptocurrencies and blockchain systems is the absence of a centralized control over the operation process. That is, blockchain solutions should neither rely on "trusted parties or powerful minority" for their operations nor introduce such centralisation tendencies into blockchain systems. On the other hand, real-world blockchain systems require steady funding for continuous development and maintenance of the systems. Given that blockchain systems are decentralized systems, their maintenance and developmental funding should also be void of centralization risks. Therefore, secure and "community-inclusive" long-term sustainability of funding is critical for the health of blockchain platforms. In this work, for the first time, we provide a systematic exposition of blockchain development funding, planning, management, and disbursement mechanisms aka "treasury systems" (for cryptocurrencies and blockchain systems). Drawing from existing literature, we identify and categorise various treasury models, thereby enabling an exploration of their properties, benefits and drawbacks. Particularly, we perform an evaluation of real-world cryptocurrency treasury system of top cryptocurrencies e.g., Dash governance system, and ZCash Foundation. Finally, we briefly discuss desired properties of decentralised treasury systems and provide suggestions for improvement or alternative solutions to existing systems or implementations.