ok so the best day of my life: i find an 8GB 3G iPhone on the side of the road, in a case, in perfect condition. It has not SIM card, so i have been using it only as a touch.. is there anyway i can JUST buy a SIM card? i would like to have unlimited texting, unlimited data (internet, etc.), and at least 500 minutes...and maybe unlimited night and weekend minutes too.. can anyone help me fulfill my dream? or do i need to buy a cheap phone, and upgrade the plan?