Soulja boy tweeted about his money madness quest completion here
Making GP in game is no problem for soulja boy. The moment he logs in, he's flooded with trades from his fans that donate him everything a runescape player could ever want. There is no better money making method in the game than being Soulja Boy. It is quite the treat to see celebrities that everyone knows playing a game you love.
Soulja Boys in game name is "SouljaBoySOD"
Add him on your friends list and maybe you’ll be lucky enough to run into him too.
souljaboy - Twitch