I got Blueprint lower ball joints from a local motor factors for mine 5 years ago, can't fault them, and they're still going strong.
Mintex brakes seem to be the brakes of choice for most and you can get complete sets off ebay for a fairly reasonable price.
Exhaust, it depends what you are after. Most aftermarket catback systems are £300 upwards, shop around. Also there are loads of threads on here regarding exhausts, use the search function.