This is input from a trusted user like myself.
We can only sell 99/99/99 accounts for around 250m-275m. If you're expecting more than that, more power to you, but you simply won't get it.
HOWEVER, at your current reputation and trust level, i'd assume you can gather 150m a piece for these.
500m, no lol. I sold a 99/99/93 with 94 Mage 99 Range 99 Slayer etc with 246 QP for 400m. So 500m, not a chance.