Most visitors get the first 30 days free when they visit the Philippines.
After that they must get an extension for another 29 days which will cost 3,030 pesos.
Then they have the option to renew for 6 months or less each time, for a total of 36 months.
The 6 Month visa extension option is currently 8,250 pesos plus another 3,250 pesos for an ACR-I card (The ACR card is valid 12 months).
The more common 2 month extensions cost just under 3,000 pesos. My last 2 month visa costs were 2,830pesos + 860 for an agent to do it all for me.