How much profit should I be making from my product?

[Katrina P]

So I'm starting a small online shop on facebook, belieber merchandise, and currently I'm selling shirts. I've only just started and I put up 3 designs already. The printing would cost P150 and the shirts would cost P100. So the cost of production is P250. I set the price at P280 though. 90% of profit will be going to Yolanda victims so I was hoping I'd be able to rack up a lot. My friends are saying that there isn't enough profit so I should raise the bar. However, I think it's already expensive. What do you guys think?

Btw, the currency is Philippine peso.

If you want to check it out: https://www.facebook.com/LBTph