This is just one guy's experience, so don't think it necessarily means what you would spend here. But I'll offer it as a guide that might help somebody.
I started keeping track of my spending in September. I've probably missed a few items here and there, but I think this is nearly complete for the full months October-April. I'll add a few notes at the bottom. This is the monthly average in pesos for each category:
Groceries 5,553
Eating out 2,465
Laundry 551
Transportation 873
Entertainment 1,321
Drinking Water 233
Rent 18,000
Clothing 368
Utilities (Elec/water) 3,136
Medical 4,071
Travel 7,817
Internet 1,017
Cell 50
Other 4,521
Groceries includes anything I buy at the supermarket, so there are some non-food items included there.
Transportation is mostly taxis I don't own a vehicle and I walk a lot.
Don't bother telling me I know my rent is way too high. If anyone uses this to figure out what Cebu will cost him, you can easily do 3000-5000 or so better than this. I will say that I'm paying for location; being in the center allows me to save on transport because so much is within walking distance, but there are cheaper nice places in my neighborhood (I'm just too lazy to move).
Medical will obviously vary greatly for each of us I've been taking some medication that costs about 3000/month. I'm doing without insurance (fingers crossed).
It totals out to P50,477, or about $1250 which has allowed me to grow my savings account a bit while I've been here. I've made no real effort to hold down my spending though I'm not rich, I have enough income that I could spend more if I wanted to. If I were trying to live on less, I'd find a decent place for 12k or so and cut back in a few other areas, and could probably get it down at least close to P40,000/month without too much pain.
Caveats: I don't drink or smoke, and I don't hang out at the bikini bars, so my expenses are lower than if I were into that stuff. I'm single -- a live-in girlfriend or wife would probably increase my expenses greatly.
I'll offer this up as just a data point that a prospective newcomer might use.