Perhaps people want to share some unlucky experiences...

Today I was at a flea market and found three Linguaphone sets! I was in a hurry, so I just quickly checked one of them: yeah, it included Lesson 30, "Wireless". And another one had all the booklets -- nice! As you may know, the Linguaphone sets are quite heavy, and carrying three required some effort.

Back home I sat down to investigate what I thought was a "lucky find". However, the one with the booklets was a different set, featuring no recording by J.R.R. Tolkien. The second one was actually a German language course! And the third, which (at least) had Lesson 30, was missing Lesson 20 (all other records were included so I guess it might have been looted).

Lesson learned: always check carefully when buying something heavy!