Vendel Garb Update

While I wait for Amalie's Snartemo band to reach me from New Zealand, I have been considering an appropriate tunic pattern for a Vendel-period Norwegian outfit, starting with the tunic.  I've concluded that it should have a simple round neck, without a slit (because no brooches seem to have been found that would be suitable to close such a slit, in that period).  Based on that information, I figure that I can make the tunic from as little as 2 yards of wool flannel, provided that it's 60 inches wide.  My current idea is to go with off-white wool, which an EBay vendor is selling here for a good price.

In addition, I will clearly need some kind of overdress, and a shawl.  Both are simple--likely my overdress will be a simple peplos.  I'm thinking of dark blue herringbone wool, such as that sold here (it's the color at the very bottom of the picture) by The Wool Connection; at 60 inches wide, I can get by with only one yard. And I know where to find plain, smallish tortoise brooches. But as I learned from pearl during her discussion of shawls, I will also need a button or disc-on-bow brooch to fasten the shawl, and I know of no vendor that sells such an item.

I could save up to commission one from a vendor, I suppose (Raymond's Quiet Press will do such commissions, for example), but to do that I need to have a better idea of how big such brooches really were. This article by Johan Callmer makes them appear to be huge! Even if I stick with a design from early in the Vendel period (when such brooches were smaller), it appears that I'd still need a brooch that was at least 4 or 5 inches (roughly 10-14 cm) long. Is that right? It's certainly going to make it expensive, even if I don't opt for any enameling.

So now I'm hunting down articles about disc-on-bow brooches, partly to see if I can find one that identifies the size of any relevant brooch finds and partly to learn more about them in general. Any information that my readers might have would, as always, be appreciated.