Thanks for your question. At this time we do not provide free or trial accounts that include vendor model provisioning. Our business account solutions include this, but as you have identified with a monthly cost associated with them.
The community evaluation (portals.exosite.com and partner sites) provide for creating what we call ‘generic’ devices that the CIK is created and has to be put onto the device manually. We do support some off the shelf development boards in those community evaluation sites also that do use client models and provisioning but of course you can’t modify them.
If you would like to evaluate the client models / provisioning functionality and are not ready to commit to a monthly cost - I might suggest contacting our sales team and they may be able to find a path based on your opportunity / project. (firstname.lastname@example.org) I can tell you we are evaluating options for possibly allowing a trial of our business account functionality but there are no decisions yet on this.