The only new products we have in the pipeline are Duet 3 main board + expansion board(s), the magnetic filament monitor, and another add-on that is relevant to particular printer configurations only. Duet 3 does not replace Duet 2 except in high end systems where Duet 2 is reaching the limit of its expandability and performance, and we won't be shipping it for several months. So there is no reason to delay purchasing the existing products.
I'm not party to the reasons why Canadian resellers have low stocks, but it may be related to the increasing demand for Duet 2 products. We have been struggling to get Duets manufactured fast enough satisfy orders promptly. However, our automated test equipment coming on-stream, and we will shortly be using a second UK-based company to manufacture Duets as well as our existing one. So any existing shortages should be short-lived if they are caused by shortages at our end.