Looks to be around $1.5-3k USD in his setup photos, likely less if he's using some used/surplus equipment, which is quite possible. Stainless fittings and tubing are surprisingly affordable. About $250 for the Deuterium.

Edit: sibling points out it may be $10k. I wonder if that price includes other equipment not shown. If not, apologies for the gross underestimation ($1.5-3k seemed reasonable - most of the equipment pricing can be looked up).