In addition to a cash gift, perhaps you can give him a box of notecards, a book of stamps and an address book with family members names and addresses inside. When you give it to him, you can tell him that TY's are a big deal in your family and now that he's a part of it, you wanted to pass on the tradition as older relatives did with you when you were young. Use some of Toots' wording about how it's nice to hear appreciation for birthday gifts or xmas gifts. Even a FB message saying TY and nice seeing you is also appreciated and helps foster good will. And be sure to set an example to him, too. Send him a TY if you get a gift from him, or send a FB message saying it was nice to spend time with him, how you enjoyed playing cards with him or whatever activity or memorable thing stands out. Let him know he should send them to non family members too, maybe a teacher who helped him with a hard subject or something like that. And when he's looking for a job, even if it's at McDonald's, a TY note thanking them for their time can go a long way in being memorable and landing the job. Basically, teach him that TY's are a valuable life skill, not just a familial obligation to score more gifts.