Crafting Grandmaster Gear of any kind takes a lot of expensive resources. In particular Enriched Dimeritium Ingots and Enriched Dimeritium Plate. If you buy them directly from Lazare Lafargue they will be more than double the cost of if you craft them yourself, so craft your own beforehand to save money (and time).
All Grandmaster Witcher Gear requires a minimum level 40 character to craft, and only Lazare Lafargue in Toussaint can craft it for you. Lazare will also craft the materials you need to make Witcher Gear, so take full advantage of his services.
The Witcher 3 Guide 