Good luck. Most of these arw grown by commercial nurseries for landscape use and are straight as an arrow. Also many have grafts that are acceptable for landscape use but are horrible for bonsai. I looked for about 5 years at local nurseries before I found an acceptable one. Mail order is an option if your local nurseries don’t get them but you have no idea what it will really look like. Take a look at the Greenwood Bonsai YouTube channel for his recent video on how to deal with commercially grown Blue Atlas cedars.