I'm not sure what you're asking. If you want to know if prqc is a reliable site, the answer is yes. It's owned by Nancy Chong and her sister. Nancy is a renowned maker and designer of Hawaiian style quilts and two fabric applique. The company name is Pacific Rim Quilt Company - prqc. It is a reputable company.
If you're asking about Aurifil thread - I have no clue, haven't used it. I have heard some people say they like it, others say their machine won't tolerate it. I didn't think it was for embroidery machines however. Nancy Chong does hand applique with it, which is why she sells it.
I just learned about this site for embroidery thread. I don't know what their shipping rates are to Canada, but their thread is on sale at very good prices.
http://metroemb.com/
One other point - I don't think thread can or should be shipped in an envelope.