trout you should be able to find a lower grade 1938 vg-f out of a dealers bullion lot as well as the 1955 in vf=ef. The 1948 is indeed tough to find in any grade. I always have trouble getting them for inventory.
The nearest coin dealers for me are 300 miles away and I doubt that they will have any Canadian silver in their junk boxes.
I got the largest part of my collection from Ugly a while back.
He has gone right off the radar since ( I hope he is alright,He is a TOP Bloke)
I have also had a lot of help from qbvbsite with the later coins
I have bought a few from eBay and I will just keep looking until I complete the date set then expand by getting the different varieties.
So I still have a lot of scope to expand this set yet
Aim to Enjoy life. You only get one shot at it