web space: an allocation of disk space on a server permanently connected to the internet

a web site: pages of information and images, linked to each other

Optional but recommended:
domain name: e.g. www.yourname.co.uk

Preparation for creating a site:
The web site designer will need a number of things in order to carry out their job:
The information that will appear on the site. An idea of the layout, how many pages, what goes where and how they link together.
Your company identity ( logos, colours, special fonts etc. )
Preferred colours and design style (look at other sites and make a list of those you like)

Methods of presenting material:
Text for the site saved as Open Document format ( .odt ) files, plain text ( .txt )
or Word ( .doc ) if you are still living in the dark ages.
Images should be saved in one of the common file types ( .jpg .tif ) they should be as big or bigger than you need on the site. The simplest way to present these is on CD ( if you work on Apple Mac or Windows Vista make sure you write disks compatible with all computers not just yours )

Costs:
A domain name will cost approx £10 per year to buy and retain.
Web hosting (web space) will cost around £40 - £80 per year depending on amount of disk space and additional services required. ( most hosts offer at least one e-mail address as part of the package ) Site design can cost from as little as £50 to thousands of pounds depending on the scale of the site.

Preparing your information carefully and providing everything required will help keep costs down.
Not changing your mind half way through requiring re-writes will avoid paying for time wasted.