As a developer, one of the most common confusion comes from the client not understanding the overall process of having a web presence.  Not having access to registrar records, the idea that by purchasing a domain they instantly have a website and obtaining the proper hosting environment come to mind as the top issues of the uninformed.

Let's start with the domain.  Pick a registrar that is well known, and accessible.  Cheapest is not always best...and make sure no matter who you assign the task of purchsing the domain, that YOU have all the access information to the account.  When you hire a developer, or more often change developers this information is vital and ties the hands of the people you have hired if it is not available.  If you have a developer make the purchase, insist on all access from the start and have YOUR email address on the account NOT theirs.

Now you have a domain....so now I have a website right?  Not quite.  You have three main costs involved in this process.  The name ownership, a hosting solution and developement costs.  DO NOT purchase a cheap hosting plan that the registrars try to sell you.  Make certain to speak with your developer as to the needs of the site and the best solution for those needs.  Again, cheaper isn't always better and there are thousands of cheap deals out there...beware.

Your development costs will vary and are unique to your situtaion.  You will find pricing across the boards and you need to find a developer you feel comfortable with and that understands your needs.  The better outfits are more costly and the products they put out are higher end.  Know your needs, and be part of the process.

To recap...you will have Ownership Costs, Hosting Costs, and Development Costs.  Those are all separate and all necesary. Retain access to all of the above and don't depend on anyone else to keep that information current.  This is your website, participate.  No one knows your business like you do and the more you are present in the process the more the site will reflect the persona you are looking to put out there.