A single 4'x8'x1.5" sheet of acrylic is going to cost about $1,600. This tank uses at least four sheets but probably six. The cost of the acrylic is 9,500. But the acrylic is custom designed so it is far more expensive than that. I woud say that the initial cost of everything is about $11,000 though I have little idea how much the sump and skimmer and heaters cost.
I would say 4,000 is somewhat high. It is intended to be a show tank, but it has scratches and is ugly, so it really is not worth much to me othe than as a cool holding tank. How much would I pay for a cool massive holding tank? If I have a six digit income I wouldn't pay 4,000 for it because I would rather just spend another ten thousand and create a masterful tank built into my home. I would say this tank is worth $2,000 to someone who is a fanatic fishkeeper and earns less than sixty thousand per year. lol at myself.