Okay, I can suggest a basic build for your needs within your budget of 15k pesos. Since you mentioned that you do not have much trust in second-hand parts and will not be using the PC for gaming, I will focus on reliability and performance for everyday tasks and programming. Here's a suggested build:
1. Processor (CPU): AMD Athlon 3000G - This is a budget-friendly CPU that is great for basic tasks and light programming. It also has integrated graphics, which can handle everyday use without needing a dedicated GPU.
2. Motherboard: ASRock A320M-HDV - An entry-level motherboard that supports the AMD Athlon 3000G and provides room for future upgrades. It has basic features and is reliable for your needs.
3. RAM: Kingston HyperX Fury 8GB (1x8GB) DDR4 2666MHz - A single stick of 8GB RAM is sufficient for your usage. You can easily upgrade to more RAM in the future by adding another stick.
4. Storage (SSD): Kingston A400 240GB SATA III SSD - A 240GB SSD for your OS and programs will provide fast boot times and responsiveness for everyday tasks. You can add a larger HDD for additional storage if needed in the future.
5. Power Supply (PSU): Corsair CV450 - A reliable 450W power supply that provides enough power for your components and leaves room for future upgrades.
6. Case: Tecware Forge M - A budget-friendly case with good airflow and cable management options. It also has room for additional storage drives and future upgrades.
7. Operating System: Linux Mint or Ubuntu - Both are popular Linux distributions that are user-friendly and great for programming.
This build should be within your budget and provide a solid foundation for your needs. It is also upgradable, so you can easily add more RAM, storage, or upgrade the CPU in the future if needed. Remember to check for any promotions or discounts to get the best value for your money.