The only one I can think of is adon network, you will need more money to get proper testing done though

Adon Network.
BTW $50 is not enough for testing.

agree with the above, $50 isn't nearly enough for PPV.

You wanting a cheap PPV network is like giving away money, you could go for adon network but their traffic is really bad.

If only have $50 save your money for free traffic, you can use it for server costs.

Only have $50 will not give you much of fighting chance on PPV.

You should raise your budget. You can't test something with this small budget. Raise your budget and yes you can try Adon Network. Best of luck.

I see everyone here saying $50 is not enough where most small advertisers start advertising with $10 budget and that is how usually they grow, I feel $50 is not that less atleast for buying PPV traffic, many network offer low start up cost, I would suggest you try to find some of them has very low minimum to start buying traffic.

If you can find ad network which has very low minimum to start then why look for these high minimum required network.

My suggestion is start with network which can entertain you in your $50 budget and still can help you

We are talking two different things here, budget and experience on CPA product/offers, if someone does not have any experience into this market, how exactly select offers and which offer may work well in which traffic then for them even thousands of dollar would not be enough and at the same time for an experienced marketer who already know which offer they should target and how to target then $50 can easily be converted into $70 or so, even with not so high quality traffic.

So its not just all about how much someone should put into it, its all about experience targeting right offer into right traffic source.