Unfortunately, none of Globe's prepaid offerings have unlimited 3G (or 4G LTE).
Try the rival network ... fortunately, they're still offering what you're looking for a little less than a thousand pesos.
Howdy and welcome to the Philippines! Hope you enjoy your stay. As for your question, you can buy a prepaid SIM card at our nearest Globe store and inquire about our data promos as well while you're there. I highly suggest GoSurf.