Yes I appreciate fees etc, but the component parts are available on Amazon individually for way less.
120mm high static pressure fans are £7 (so £28), an AC power-supply fan controller £11. IKEA filters are £3 each, so £12. So we're looking about £50, be generous and chuck in another tenner for 3d printed ABS and screws etc. £60 all-in at 1x retail/Amazon prime prices, delivered to my house.
If I was doing this at scale I am sure I could get lower than the retail Amazon prime prices. But even if I couldn't this is about half of the £130 RRP. Yes there are labour costs to assemble this but this is not exactly a swiss watch and looks like it comes flat packed anyway?