I have learned nextjs and mern stack. Now I want to build real life business solutions for people. And I want to know from people from Bangladesh as I don't know how people make solutions for small businesses without buying high cost hosting, dbms like mongodb, authentication providers.

But got some issues:

• how do I use authentiaction cause paying nextauth, superbase or firebase will increase the cost dramitically? How real projects handle this stuff?
• how do you setup database cause it will increase the cost also if use mongodb atlas?
• what to know about vps and load-balancing? Idk about these stuff