Is it possible to have read-only users that we don't pay for?

[Dave DeCaprio]

We'd like to give our customers read-only access to a private repository that we use to share code samples and tutorials.

Is it possible to do this without having to pay a monthly fee for each user?  We already pay for all of our developers to have full access to those repos, but we'd like to be able to give wider access to our customers.  We can't afford to pay for bitbucket accounts for all of them.