if you head to Jira Homestay (almost across from Crazy Horse Buttress crag entrance), you will meet many climbers. You can also grab some food there.. they welcome people to sit and hang out there even if you aren't staying there. You can take a cheap (I think it was around 35 or 40B or something similar) local minibus to the crag.. tell the driver you are going to Jira Homestay. Pick it up across from the flower market in Chiang Mai. Google for details.