I read about 2 things: drive large traffic and expand to bidding platform.
What you should be doing is the million dollar question: how can I spend $10 to get a sale and profit $20 from it.
Notice: sale, not traffic or user.
Like you mention, there are tons of ways to get traffic but you don't want 15 year olds from India by the million visiting your site. What for, right?
The way I would approach it is via trial and error. What works for your competitor may not even work for you.
But please, never go on all fronts. That never works. Every startup with limited resources that I see create a Facebook Page, build a blog, doing SEO, email marketing and so on, they fail.
I can take a call with you to understand better what resources you have and give you my opinion on picking one channel to try for X amount of time, what to do, what to expect and how to track success.
