There is a major article on Dominion Land scrip by Donald M. Stewart in the CPMS Journal for 1979, spread over three (quarterly) issues. It will no doubt continue to stand as the reference work on these notes for a long time to come.
If you are a CPMS member access to the older journals is readily available.
At least twelve of these pieces were offered by the same vendor on a certain internet auction site (you know the one) between Nov. 2006 and Jan. 2007; one lot consisting of 2 $20 notes with deer at the centre sold at $192 for the pair. It seems to be one of the most available varieties.