Screwed without written contract?

Hello,
I have been doing freelance work for an advertising company (actually run by one guy) for about a year now. We have never written a contract, and it was never anything I really considered, since he would always pay me for all the work that I did right after. Being a current student, I also have no experience or knowledge of contracts, so I just never questioned it. I needed money, and it was an easy way to help pay the bills.
Well now, it had been nearly 4 months since I have finished about $600 worth of work, and I have not received a single penny. I have contacted him about it, and he always gives me the runaround, and same excuses of being busy, that he will get back to me, that he got screwed by a clients and things are tough right now. He finally contacted me saying that he would be able to pay me at least 25% of the total.
I have yet to get paid anything at all.
My assumptions are that, this is a lesson learned, that without a contract I am screwed, and I just need to let go of the idea of ever seeing that money.
But another part of me has hope that maybe there IS something I can do, that I may not be aware of.. I hate the idea of him taking advantage of me and my time, and other ignorant students like myself, knowing that we cannot do anything because we never questioned the idea of a contract.
I have heard that sometimes verbal contracts may be enough.. but I really don’t know if this is something worth pursuing, or should I just let go, and learn from this mistake?

Feedback is appreciated, Thank. :)