I want to get real readers (not just impressions) on a blog site and buy traffic for that purpose. Topic is "psychology".
Have tried pop traffic from propeller but that is not really working well. People leave instantly. But my goal is to keep them on average for 1:30min (that's what I see from search traffic).
What would be the easiest and most efficient solution with a budget of 50 USD / month?
Psychology is such a specific topic that interruption marketing like pops won't work.
You should rather use click traffic where the user decides himself if he wants to click the creative to visit your site or not.
That way you should get better time on page already.
About the traffic, you could either try push where the message/creative is not connected to a specific website with specific topics.
When you want to use other traffic like banners or native you should make sure that the trafficsource has websites related to psychology to show your ads.
Facebook or Adwords could probably also work very good, there you can target pretty good by audiences/interests or keywords.
Downside is that there the budget is probably too low.
Talking about the budget, $50/month is generally pretty low.
What geos are you looking for and how much traffic do you expect to receive for $50?
Edit:
Geo is DE.
I set the budget so low because I want to test waters first. It took me several weeks to get some keywords ranked on google.
Also did some FB posts and send my small army of artificial FB users into various related groups. Was a hell of work plus proxy and SW licence are a bit too pricey for my small project.
Cool thing tho is that the FB posts are somehow recognized as backlinks (at least looks like that on monster insights).
So the basic idea is to see if it makes sense to throw some money on it. I measure "success" in terms of subscription to newsletter.
Currently it is more like a passion side project. So no solid business case yet.
Hi @larsometer, If you want extended visits , you should try doing Push instead of POP. i believe it will help you 
Good Luck !
FB traffic will be the best for this, since it can provide the best value and still cheap clicks with the right targeting, as stickupkid mentioned.
And a small suggestion: promote specific blog articles, not the blog main page. You need to catch the users attention with a particular topic straight away, that you write about in the blog, don't make them search for content that they MIGHT like. And if the content is good, people might actually share it on FBm which would mean free clicks.
Push traffic can be good for testing the concept of the blog, these clicks can be cheap too and you can watch the behavior of these users to improve the overall usability. But, based on my own experience with trying to jumpstart a website with paid traffic, push clicks are of WAY lower quality than properly targeted FB clicks.
You could also check your trafficsources if they offer native ads as well.
Then you could test it alongside push.
If this is an actual 'blog' where you want long-term readers who will become engaged with it, then I would say Facebook via targeting people who are fans of similar websites and blogs; YouTube, targeting subscribers of channels very similar to your website; Quora, targeting people searching for the topics your blog covers; or Bing search, doing the same.
If it's a very broad-themed site like everydayhealth.com or psychologytoday.com or something like that where the articles appeal to 10-40% of the population and where your monetizing it via ads, then perhaps push or native or something could work. It almost becomes more like content-arbitrage at that point.
Really depends on your goals for the site.
Can also try to invest that budget into building an audience, e.g. FB group, mailing list, etc., and then sending out a post/email to the audience every time you publish a blog post.
And of course to build that audience, you would want to target by interest - pop won't work for sure, and push most likely won't either. FB has been suggested - I feel this would be the best place to build the audience as well. Google would likely be too expensive.
Guest posting may also be a good way to get readers.
Taking a step back though: I'm seeing the trend that people are gravitating away from reading long content like blog posts, and moving more towards shorter content such as FB posts, or better, videos.
Publishing videos to youtube regularly may also be a good way to build an audience, as opposed to a blog.
And if you do build an audience on FB, such as a FB group, you can upload videos on FB for your audience or do live videos. The latter is under-utilized IMO and can yield really good results. With so many businesses trying to catch people's attention online these days, direct human-to-human interaction by showing your face in live videos can give you a big edge over competition that are only sending cold traffic to a sales page or even to a "live webinar" - lots of people are catching on that these are pre-recorded so they don't work as well as they used to.
It would be good to figure out how you want to monetize the audience first, before planning out the rest - e.g. how to build an audience, what type of an audience to build, how to keep them engaged etc. That way you have a definite direction you can angle everything else towards.
Amy