SuitSupply source their fabrics from medium- to high-end Italian fabric houses. With their scale, they can buy up big and so can keep prices down while providing a low-margin windfall for said suppliers. It's a clever model, better I think than trying to incorporate fabric production into their otherwise vertical structure.
So generally the fabrics are better than what you'd expect at this price point. Brown prince-of-wales sounds outstanding. What's the cut? Soho cut is pretty extreme and I'm only barely getting away with it, having slimmed down a bit over the past few months. Look carefully at the measurements they provide for each garment and make sure they work for your build.