Is this something you plan to do with your students yourself, or would you be looking to bring someone in to do something?
For example, if you have in your circle a massage therapist you could see if they would do mini chair or feet massage for a very discounted fee, …. they get to give out their info to a group likely to be interested, and you get something cool. Or if you know a chef who specializes in healthy food, you could offer a ‘sampler’ lunch for a small fee.
Both Janet and Karin’s answers are great, and if I were in your class would really be happy with either one. The only thing is that things like self massage, myofascial release and meditation, or even something like a gong bath, are all wonderful, but to make something like that work you need to pick something that you are skilled in, or make sure to get some training before offering it.
some things do not work well together, I think. Years ago I went to meet with a lady who wanted me to offer some yoga in her salon. I knew as soon as I entered it would not be possible. Yoga requires good breathing, and the acetone smell was pretty overwhelming.