@mae_oz hello.. If I may ask, taga san ka dear? You can visit yung trusted travel agencies sa area niyo and ask them for available student fares.. You can also opt to go directly sa office ng airline for student fares. Kung san mas convenient for you. Make sure you have a copy of your visa grant notice.
Yung sakin sa Makati.. Fares would vary depending on your departure date (usually mas mahal ang fares pag weekend) and dun sa available booking class.. Meron kasing certain booking class yung mga airlines who offer student fares.. Kung hindi naman na available yung booking class na yun for student fares, ask them for the lowest available booking class..
Make sure that you don't book the exact same flight details (e.g. Same date, airline and flight number) with 2 different travel agencies. The airline would cancel one of the bookings kasi dupe/duplicate booking yun..
Hope this helps.