SusieQOH, if I am thinking correctly you have a Bernina with a non-standard bobbin size. The problem I had trying to buy Glide locally was I could only find it on pre-wound bobbins and my 820 has an extra large proprietary sized bobbin that isn't L, M, or 15. To get the pricing on their website I had to fill in information first and I wasn't going to do that... so I got a cone of So Fine from Superior, I've been ordering directly from them for about 5 years now. First started buying prewound bobbins for my friend's machine which was M size and again, although I could find L and 15 locally, not many M. Personally, I grew to love prewound bobbins and while the Bernina is easy to wind a quality bobbin, if I had the embroidery module I would really want to be able to just buy a ton of bottom thread already wound.
My Aurifil thread I look when I am ordering things from Amazon if there are any sales going on, I seem to do pretty good that way. I have a price I'm willing to pay and so I wait for that.