This is an interesting topic, in part because I have been considering for a little over a year whether to get my CPLP or other ISD certification. Being on the job market, it seems at least 1 of every 10 job postings asks for it, and some explicitly tell you not to apply if you don't have one. I figured $1000 US is not bad, but at the same time, I've been working in the capacity for years, and would basically be paying $1000 for what seems like simple validation to others of what I already know. On top of that, my Masters I am currently in the middle of earning covers material in the CPLP, so perhaps that's my answer right there.