Asking a past professor to teach a workshop/short course
In general, the expenses you've listed above (travel costs, local accommodations and meals) are typically sufficient. Registration fees for the workshop would also usually be waived.

One other thing you might consider offering, if funds are available, is a small stipend to be used by the faculty member to sponsor a "young researcher"—a graduate student or postdoc—who can also attend the workshop and take part, perhaps by offering a poster or contributed talk. (Or, if it is not possible to offer a stipend, perhaps the registration fees could be waived for the young researcher instead.)