Until now I only read a book on DBT and my experience is limited to mindfulness practice. There was an interesting thread on this subject lately on this forum, I'll put a link here if I can find it later. Mindfulness practice doesn't work for everyone, and even those who benefit can't always apply it, speaking of myself.

With a couple of days of intensive practice I could concentrate on my breathing, or on my legs moving and the feeling of my feet touching the ground, and be happy. I need to be in the right mood for it, but if I am, just practicing mindfulness can make me happy. For me this ability came on the third day of intense practice under retreat conditions, and I think it's well possible to miss out on this aspect of the practice during a course with psychologists.

A 10 day course in Thailand cost me $50 in total ($5 per day), accommodation and good food included. They had a British monk as a teacher, incredibly good value because Buddhists have it the teaching needs to be given for free, though some might consider 30mins of daily mantras as a hidden fee