You need at least a junior member to rank up, and you need merits too to advance, but if you buy a copper membership you can participate right away but I don't know the price now, I read here that it is getting pricey if you want to know more go here
https://bitcointalk.org/index.php?topic=5097960.0, this copper membership are for developers who want to make an announcement on their new project but can be used too to participate in a bounty campaign who just sign up here.