On a limited pension, I had to look for an inexpensive supplier of thread. I ordered from this company and so far have been satisfied. The thread is not as hard finished as Guterman, but it's strong, non linty and comes in pretty colors.
http://www.threadart.com/c-64-polyes...ng-thread.aspx
I also ordered the varigated embroidery threads in polyester. They are very pretty and FMQ very well.
http://www.threadart.com/c-8-multicolors-polyester.aspx
I received free shipping as a Christmas special, too.
edit: I haven't tried on Miss Elna yet. That will be the test as she is a little selective. The 301 and the 15 clone are happy with these threads.