I purchased discs from a seller on eBay. Brand new grooved. They are M-Tec brakes. Time will tell how good they are and if they warp.
The pads were Brembo. So should have no issues.
You can obviously build the kit to whatever budget you choose. Dave can supply j-hooked Brembo discs and you can buy pagid rs4-2 pads. But with all that you are looking near to £1100+ for the setup.
I'm happy with my kit. Much better stopping power over standard, but on a very tight budget.