If you want to stay long term in the Philippines you should have a health Insurance.
If you are below 60 years of age and if you travel to your home country al least once every two or three years, you can easily be covered by one of those time limited (3-5 years) but long term travel insurance plans which are available from some international insurance company as well as domestic companies in your country.
If I stay in in the Philippines, always for period of 6 month, I am covered for any ambulant or hospital charges for only 35,- € per month or less. You can easily go with one of this companies until you reach the age of 60 or 65 years.
From 65 years up, the monthly fees for those plans rise drastically up to 300,-€ or 400,- € and you really have to think about, if you can still pay that amount every month.
You should take in consideration, that you can easily pay for out patent care in the Philippines by yourself. Only in patient hospital charges for operations, X-ray, CTC or what ever can quickly overshoot your budget.
Hospital Charges Only
So you might want to look for an insurance company whose insurance plan concentrates on hospital charges only and leaves the out patient charges to the patient. The only company with such a plan I know, is the Healthcare International in the Uk!
They have an insurance plan called Emergency Plus, which covers only hospital and emergency charges, it has a high deductible, thus, is for emergency only or lets say for people who never get sick and who need an insurance only for emergencies. Click here to download a plan comparison (PDF)!