I've made it to the 360s with 1 prayer pot and a crystal bow (achievement diary ftw). The real challenge comes when you start getting 360s (mage), 180s (melee), and 90s(range) all coming for you at once, and you have to make good use of the safespots and lure the monsters well. However, some people have this whole system down (like Muggi :D ) and would have no problem doing on it with an account of your stats.