The best thing I can say is, get it price checked by Gold4RS. You're account is only gonig to sell for max 1.5x - 2x what they offered. Then convert into GP at $0.50/m. People say the accounts worth 500m, but I don't think it would sell anywhere near that because nobody is willing to risk 500m on an account. Hope that helps
500m easy in my opinion, get some more non combat skills and the price will rise dramaticly, i wouldnt sugest selling it though... unless its for a good purpose haha