Vray costs 425€ or (70€ monthly), it includes CPU and GPU engine, and Cosmos assets. Vantage is free right now.
629€ is the price for the whole Vray collection that includes Vray for every platform (C4D, Max, Maya, Rhino, Sketchup, Unreal, Houdini, Nuke etc), Cosmos assets, Vantage, Chaos Scans, Phoenix for fluid simulations, Chaos Player and some Cloud credits.
That's the official price, you can still get it for less from other resellers.
425€ seems reasonable for what you get if you consider that otherwise you have to pay for a CPU engine like Corona, a GPU like Octane, and a RT engine like Lumion, all disconnected from each other while using Chaos ecosystem you build your scene once and it will work across the whole platform.