Try www.atlantathread.com
They have Egyptian cotton, 40/3, tex 45, yes, tex 45. Very strong, comes in 12 colors, 6000 yd cones for ~$12 each. I use it for most of my machine quilting. They also have Signature, size 50, 3000 yd cones in assorted colors for ~8.00. For regular sewing, I order Guterman from them also. $2.95 for 1100 yd tubes, over 600 colors available or on 5500 yd cones for ~13.00. They are very prompt with their shipping and usually send out the day you order if you get it in before noon. They are the only place I buy thread now...
Emma