Hi Mark, first off i would advise against "mixed" seed as 2 to 3 years later you will be here in the "Cacti Identification" section asking us what they all are
been there done that
have a look at http://www.succseed.com/
click on "seeds-cacti" then on "Rebutia"
you will find 19 pages of named Rebutia seeds, a lot with images to see what you are ordering a lot come with field data too
seeds are a USD or so for a pack which will give you about 20 plants per pack if grown well.
postage and payment are very reasonable and they accept paypal and cash in notes (USD) which i suspect are easy to get in Canada
seeds are always fresh and grow well, i can thoroughly recommend them
i am at this very moment repotting Rebutia and must have dumped about 1\2 million Rebutia seeds in the bin.................
see my topic later to see why