Cost of switching Web Hosts

I am about to embark on a project to move a mid-size website (approximately 200 pages) and the accompanying SQL dbase to a new hosting environment. The site has been built using Microsoft.NET framework.

Wondering if anyone might have an idea of the costs involved with transitioning the site to a new web hosting environment.

Additionally, I am changing developers in the process as well, to what degree will the new developer and the old developer need to collarborate to make this move a success?