Hi. From what I know, it's really necessary to have some funds in a bank account (either your own or a family/relative) as "show money." If you don't have it in your own account, you can draft a letter of "sponsorship" from a relative/family who has that amount in their bank, and ask for a copy of their bank certificate. Another option is to get a loan/borrow from a third party (not sure if bank loans would work though).
Even though your budget is Php 100-300k, you still need to show that evidence of financial capacity for your living costs UNLESS you have enrolled in one of the big universities (USyd, UniMelb, UNSW, etc.). Getting an eCoE from them means paying the pricey AUD15k (around Php 600k) for the first sem, but when applying for the visa, you won't be required to show any other proof of funds anymore (at least according to the <a href="https://www.homeaffairs.gov.au/trav/visa-1/500-">Document Checklist Tool</a>. I think it's much more economical to go for the "sponsorship" route so you can stick to your tuition budget and not shell out more money than necessary.