Hardanger is normally worked in two weights of threads. For fabric with count of 22 through 25 I use size 8 and size 5 threads. Kloster blocks are worked in the heavier, thicker size thread which would be the size 5. Bar weaving, and fill-in stitches are worked in the lighter size 8 thread.
For further discussions of threads view my blog page: Needles and Threads
If ordering online I have found it is a good idea to always check the S&H costs and shipping time before clicking that submit order button.
Near all of these below stores carry threads and most offer cut-to-size and pre-cut size fabric pieces. The below photo shows a small slice of Needleworkersdelight order page where you specific pre-cut size and fabric color choice.
123stitch.com/ (threads, fabric)
www.stitchers-paradise.com/ (threads, fabric)
needleworkplus.com (threads, fabric)
needleworkersdelight.com (fabric and custom dyed fabric)
http://www.nordicneedle.com/ (threads, fabric)
http://www.needlestack.com/ (needle in a haystack)
Stretcher bars, tacks and removal tools: Nordic and 123Stitch.