Speaking from experience, it's FAR more costly to build this one yourself, once you factor in time, paint, supplies, etc. Just sculpting all the little accessories would take a long time. Sure, you can buy a lot of the things piecemeal from 3d artists on eBay—some good stuff for sure—but you still have to paint and generally modify ****. This is a much easier alternative.
I mean, if you value your time at $0 then you could build it cheaper for sure. But it's an endeavor that takes a ton of time to do well.