And yet another vote for.... Pimsleur! The 30-lesson sets are excellent. (Some of the more popular languages have several levels -- like 1, 2, and 3 -- each of 30 lessons.)
I've studied (or refreshed) several languages using this series. They do indeed have a course in Greek, which I have used. (I think the Greek course has only 20 lessons.)
I have also been successful in getting bargains on Pimsleur courses on eBay. Of course, you could also sell your course on eBay after using it, if you are so inclined.
Kathy