First off, I’m a mason, not a concrete guy, take what I’m saying with a big grain of salt. My guess? Definitely not pocket change, but that stuff wouldn’t exist if it was more expensive than building it new. Building that new could be between $1500-2500 depending on various things. If you wanted to DIY building it yourself it would be like $300-500 or so in materials. My guess would be between $500 and $1000. But it could be $200 or $2000 for all I know, lol.