Did you say 8K for one week backpacking kind of trip where you utilize only budget facilities????

As far as I know, you can rent a very nice studio or small apartment in a good location in Cebu for 1k per month and not one week. The Air ticket is 3k. 4k can be enough for good food for one month. In my opinion. 10k is enogh for a wonderful one month trip in Cebu. 8k won't be enough for even 2 days as well. Depends what are your attractions and destinations. For example,If your attraction is night life and women, then 8k wont be enough for 5 days