Here are some alternatives to acquire traffic:
A single provider isn't going to give you the scale that AdWords and Facebook have. So you'll have to diversify.
You should also look into optimizing your existing campaigns with AdWords and FB. Are you targeting the right keywords on AdWords? Is your segmentation optimal on FB? Here is an answer with some strategies for FB.
Reddit ads can work well if you understand the audience and target relevant sub-reddits. Reddit has huge reach, and there are sub-reddit communities for everything under the sun.
Here are a couple of relevant writeups on advertising on reddit:
Yahoo! Bing Network is more affordable compare to Google's AdWords platform.
However, expect for a lower volume of traffic to compare with Google AdWords.
You can also consider the following...