I buy variegated all the time.
http://www.hawthornethreads.com/threads/aurifil
Hawthorn Threads has the entire Aurifil collection -- every color, even variegated (they're last on the list) in every size & weight. I would not run anything heavier than their 28wt through a domestic machine & really that's probably not the best choice for FMQ. 40 or 50wt would be better choices.
EDIT: If you go with a 40/50wt, you can use an 80/12 needle. I've used Microtex, top stitching & quilting needles. I like the quilting needles the best, but the Microtex are also great. For the 28wt, I've successfully used top stitching & quilting needles at either 80/12 or 90/14. I personally haven't had luck with Jeans needles for quilting, but then again, I've never tried to feed a 12wt thread through my machine. I will say that both the Aurifil 12wt and the Aurifloss have given me really beautiful results with handwork (quilting, embroidery, raw edge applique) and they are definitely high quality threads, just super, super thick.