Recently, I purchased a theme called Foot, it consists of all the features that I need - masonry layout, front-end content submission, Facebook login, responsive menu for tablets and mobiles, review system, infinite scroll. Interested? Here is a short review of the theme.
Btw, do you know that ThemeForest has added a support feature? Say, for a regular theme license of $59, you can extend support to 12 months for an additional $17.70. What does support include? The theme purchase includes any updates made available by the author. The item support mainly includes availability of the author to answer questions. I reckon with this new author support service, more authors would be eager to provide a better support service. :)