I'm wondering if you don't have enough ads, or they aren't blended well, or if your niche just pays poorly, because that much traffic should be able to easily generate from $700-$1K in AdSense alone without trying very hard.
For me, Amazon and CJ have traditionally stunk for monetization, but Share a Sale has done pretty good. LinkShare has potential if you can stomach their user interface, it's just not worth the few coins it generates for me to go digging through the poor interface.
Can't put my finger on it, but something was rotten with CJ, like cookie washing somewhere or something like that because at one point I did really well with them and the click throughs held up but the payouts just dried up and blew away so I dumped 'em. Went back and tried them once more, same exact thing happened, that it started out big and suddenly dried up again. Not wasting my time playing that game a 3rd time.
In the end, the simple answer to all your questions is do A/B testing using various ads, networks and services until you find the ones that pay the best. You may find some services pay better on one page while not on another.
The only thing I've ever found that paid well site-wide was contextual ad services like AdSense, but then you still have to experiment with ad sizes, placement, fonts, text and link colors to figure out what attracts your visitors eye best.
With your traffic and your poor AdSense payout, you might want to consider soliciting a few direct advertisers and give them run of site ads for a flat rate. You could easily make more money selling several dedicated ad placements than what you currently earn per month via AdSense.
[edited by: incrediBILL at 2:11 am (utc) on May 16, 2012]