Purchase - Historic Enterprises sells historically accurate costumes for men and women. Each item in their catalog actually comes with an accuracy rating! Not the cheapest, but well researched and, from what I've heard, well constructed. This basic ladies' viking outfit, consisting of linen under-tunic and apron dress, costs $150. It's available with a wool over-dress and a head covering for $160. The individual pieces are also available separately.
Sort of what I want, but I would remove the ugly leggings and wear a wide cloak around it. Definitely the right time period (Dark Ages/early medieval period). This is more Viking, and I'm aiming for more Frankish.
Geometric Construction of Tunic. This page has DETAILED INSTRUCTIONS ON HOW TO SEW THE GARMENT TOGETHER (which order). While I disagree with some of the dating she mentions (they did not stop wearing rectangular construction garments in 1250), her instructions on how to sew the garment together are detailed and clear.