Hey Jim, I am currently searching for the same. The only one I have seen which is around $24,000 is the one from Cal State Northridge. This one actually specializes in Assistive Tech versus something with a more Special Ed focus. I currently work as an ATP and I would like to get another masters to change careers as I currently am just about done an MBA. I see you did the cert from Dominguez Hills, how did you like it? I'll watch the thread to see if anyone finds any others. Good luck!
I don't know if this helps https://www.bgsu.edu/ecampus/programs-and-degrees/med-special-education-assistive-tech.html
If a certificate will meet your needs then you should check out the Information Accessibility Design and Policy program through the University of Illinois: http://online.ahs.illinois.edu/iadp/ It's a total of three classes at two credits each at a cost of $904 per class. These are evidently considered graduate level classes, but the program is a "Certificate of Professional Development" as opposed to a Graduate Certificate.