Well, after looking at monster tanks, or really any tank above 150 gallons, I've gotten quite frustrated. I'm looking into a monster FW tank. I've looked a lot on this site, but can't find an aprx. price on a monster tank. I'm looking around 2,500-5,000 gallons. My LFS gets fish that would be great for a monster tank sometimes, such as aro's, gars, shovelnose cats, and random other things like so. They even have a african goliath fish right now. Anyways, I want to know just some price around the cost for a tank around that size, whether it be DIY or not.
I've got about $4k in my 1000 just in materials, and not including glass. Add another $500-$1k for the glass and your at about $5k. Of course, economies of scale comes into play here too. A 2500gal would probably not cost that much more than a 1000gal. Once you get to 10000, depending on construction methods, I would think 2x the gallonage for cost.