I would happily support the network if I earned some profit, but I cannot do it for free. Thanks for helping!
You will not be earning a profit most likely. I can't guarantee that but considering what the manufacturers say they will be delivering you cannot profit.
Having said that, you can still buy some hardware. I would start off cheap to get your feet wet and learn. The R-box is a nice little miner and here's a review:
https://bitcointalk.org/index.php?topic=639030.0You could find an old Antminer S1 but they are noisy as hell but probably a better value keeping to the $1/GH rule.
Spend the rest of your $600 on an exchange and get some bitcoin directly from other miners. Make sure to learn how to protect those coins.
I got my R-box using Amazon gift cards, so it was essentially "free" and I also have 4 U2's - brings in about 80k satoshi per block (and falling hella fast) mining on Bitminter. That being said, its a great miner once you get it up and running (use a PC - if you can get that thing configured and running, you can get any miner set up).