Nandana Singh has done a great thing by programming a good quality free collar!
Open Collar is a free, open-source fully functional collar with full permissions. It has many features that collars costing L$100s do. From version 2.1 it also includes support for the Restricted Life Viewer.
Since there are full modify permissions there are now a number of versions, including a punk version!
These are freely available, for example from the "Free Scripted Collar" vase at the freebies section down the Hall at the Cellar or from the Cellar shop (http://shop.onrez.com/San_Mauvaise and press the "Yes" to show mature items like the collar).
You may pass it on to others, but please at no cost and with full permissions (please read the license notice that comes with the collar).
PS. If anyone knows any other good quality free items that we could help distribute then please tell me.