Truth behind Runescape Gravestones?

OK, I found this quote on RuneVillage forum:

"You may visit Muntabii in the Mage arena found in deep Wilderness to reserve your gravestone. For 50,000gp (50k) you may set your account to keep all your items when dying, even when skulled or attacked by another player. For 100k, you may also buy other peoples items from there gravestones..."

Couldn't find the original source, though. Does anybody have more information on the subject?