Your site is quite huge. I believe the customization will include better interfaces, additional dynamic database integration, personalization, and others that not notice by me. Should I be successful in this bid, I would also include content management system for you to easily manage you content. Maybe you need to segregate the registered clients into certain sales zones. Well that can be done. Please post your details so me and other bidders could decide the budget and time-frame correctly. If you have found the coder locally please advise so. Thanks for your intention.