He doesn’t wanna buy. He wants to rent. Of course it’s impossible to answer since everyone’s needs, tastes and living arrangements are different.
But here’s a baseline to build from: Assume 400,000 pesos per month (as of today, 430,000 pesos a month from now), the equivalent of around 400 blue dollars (as of today) for a single person preparing his or her own meals, and with a modest social life. That covers health insurance, wifi, water, gas, electricity, building expenses (often the tenant pays these), laundry, supermarket purchases, a daily coffee, a meal out once a week, a haircut, bus and the occasional taxi fare. For someone who lives bigger, grow the budget from there. The amount includes 40,000 pesos for health insurance. Subtract it if you feel healthy. Then add the rental costs depending on what your expectations are.