I've built an above ground pond with cinder blocks, wood, and a pond liner. The pond liner being the most expensive part. Really depends on how ghetto you want to get. I also built a filter for it out of a plastic plant pot and the most expensive part was the water pump. All in all I was able to build a roughly 375g pond for $300
I'm new here and can't seem to figure out how to change my profile image. I tried to click help but it was no help : ( if you could help me I'd appreciate it. And just so I don't mess up the topic in this room here is a photo of the pond I built : )