Instagram has over 30 million users on iOS and over 1 million users on Android. Now Instagram is getting close to raising a Series B round of funding led by Sequoia Capital according to sources with AllThingsD. The $50 million investment would peg the valuation of Instagram at about $500 million. DST Global is also rumored to be involved in this round. Even though Instagram does not have a revenue model right now, there is still a high number of interested venture capital companies.