Why do I get emails from recruiters regarding jobs hundreds of miles away?

This has happened several times in the past but the most recent one really made me scratch my head.  I got an email from a regional firm recruiter asking if I was interested in making a lateral move to a position in a different city.  The email mentioned nothing about relocation, so I'm assuming that means they want me to do this all at my own expense.  What is the point of these emails?  Is it really that difficult to source talent locally?  Do they expect to find a sucker who is willing to pay a couple thousand dollars to move for a staff-level public accounting job?