Advertisers are not going to be too enamored with an Alexa ranking as that does not always equate traffic.
If you have a decent number of unique visitors then you may have something to offer.
Let's suppose you have a blog about tennis shoes that gets 20K UV a month. You can either go to a site like buysellads, buysiteads, etc and get set up and start generating money from advertisers who want to market on tennis shoe sites, as those kinds of sites make it easy for a website owner to connect with advertisers.
But, you need some decent unique visitors for that to attract advertisers, not a decent alexa rank.