Business Training - Booking / Information Sytstem site

Training provider (similar to Hotel booking) engine website that essentially has 2 parts. Online availability search where availability and prices are retrieved and displayed to the user. One part is the public interface - users will browse, locate and find available spaces upon training courses the company is running. They can book a place, pay by C/Card and receive an email back for their records. When a user makes a reservation, they automatically get a user name and password for our site allowing them to login later, change, cancel, and make new bookings etc. - this site may be used for single person users or businesses booking many courses at a time. Secondly we need access to the management information via internal 3 tier logins - admin, management and internal user who have access to different information. i.e. admin can hack around with who booked what, cancel, change etc. managers may want to drive out reports about sales, creating new courses, killing old courses etc. We will need to port user / contact information from an existing local database into the site prior to going live/testing. Also the ability to manage ad banners within the site is also a requirement. The last thing I need is to clean the site up for SEO purposes. The site must look clean via a text browser. After we converse and I show you what we have and together with what I want, I will ask for one price, not one which multiplies after completion. I need guidance all the way, your requirements upfront and someone who can show me a similar site sample.