Usually, some scholarships are given by private medical schools (like UERM) to incoming freshmen who meet a required general weighted average during college, usually the cum laudes of their batch, irrespective of course or school. This is called entrance scholarship. It usually lasts for the 1st sem only. Range? depends on the school.
After the first sem, you can start applying for academic scholarships offered by your school, or by its alumna (requirements are listed in the student handbook or you can ask the Registrar office of the school). Some private individuals/companies also give scholarships but you'll have to ask around. You'll need to maintain a GWA of 1.75 or higher to be an academic scholar and some require proof of income because they only select those who really need it. Discount is usually 25% off the tuition fee.
Call the schools you're interested in applying and ask about their current tuition fees. Tuition for UERM is around 70k (1st sem SY 2006-2007), so I'm guessing all other private schools probably are at the same tuition fee range. UST is probably at the 90 or 100thou already (when I went to med school 5 yrs ago, their tuition was at 60-70thou already).
Schools allow you to pay the tuition fee in installments, although you'd have to ask how it works.