Several other marque forums I belong to now have club discount deals with EuroCarParts. I find them very competitive and superb delivery even without the discount. Usual disclaimer - not an employee, just a happy customer.
Conjure up a VAT registration number and the discount is exceptional. I've seen parts that are well over £100 retail priced at less than £20 on trade. It's remarkable just how much average joe public gets mugged off sometimes.