Definitely hit up Craigslist on a daily basis and look for deals in your area. I usually search for "aquarium" and "fish tank" in separate searches. Then sort from newest to oldest and look down until you recognize something from the last time you looked. You can find crazy deals on Craigslist. For example, I got on it one time and there was an ad up for a 150. The guy still had it up and running with the stand, filters, lights, everything. However, his heater had gone faulty and killed all of his fish. He wanted it gone and gave it all away to the first person that came to haul it off. All of that, for FREE. Unfortunately, I didn't get it because it was gone by the time I saw it. Lol
Just buy little bits and pieces at a time and spread out your purchases if you need to. You will end up with a better system than if you try to skimp on stuff. It might take longer, but in the end, I think you will be glad you waited.