What is the cost of STP system?

Inquiring about the cost of a STP system, I'm curious to understand the financial implications involved. Could you elaborate on the various factors that contribute to the pricing of such a system? Are there any upfront investments required, or are there ongoing maintenance costs? Additionally, does the cost vary depending on the size or complexity of the STP system? It would be beneficial to have a general range or estimate of the cost, as well as any potential hidden costs that might arise. Understanding the financial aspect is crucial in making an informed decision about the STP system.