Firstlu, use the dealer prices for negotiating but you wont have to pay anywhere near that much.
Best case scenario;
Pads and discs from a trader will be cheaper depending on what you want.
Upgrade the exhaust, plenty available for good prices.
Cant help you with the cat issue, hoepfully just a weld to repair.
Stonechips, would hate you to feel left out
To me, that sound like a great price so the other issues wouldnt bother me too much.