A good eco its the one that has many ways to drain itself. It could be cars, skins, Jobs? Anything that will make people waste money its a decent one. Because everyone hates having people with 50m in the bank, you could make the rich pay more taxes for products? But you'd have to make an addon, and I doubt you can if you are asking this.
Not exactly sure what youre asking or how to give an answer without more info but if youre wondering about eco then like miguelo said you need stuff thats gonna have players grinding to spend big money on. Cars, special guns, other weapons, etc. Theres no 1 and done answer, its just gonna take tweaking.