I'd value EM sashes as the same as "Member of the Royal Britannia Guard" sashes. So in the 1-5 mil range depending on which EM. Certain sashes belong to EM's who were let go or retired so those will probably have more value.
The value of these sashes has definitely plummeted since Messana came out and said they are not supposed to be rare. Also take into account the new "vending machine" distribution method where these sashes are being handed out like candy, as well as the fact that I have gone on record stating that I never valued these sashes as anything more than an oddity as opposed to a rare. So as a result, some people might find more value in them than I would.
Yes and no. The Vending Machine has been introduced on 3 shards thus far and 4 out of 6 EMs have put a "date" stamp on their sashes, i.e. 2010 which makes all the previous sashes from these EMs much more rare. So, the sashes prior to 2010 should still hold their value around the 5-10 mil range except for Cyano Razik. And some can even fetch upwards of ten mil for those who wanted to complete their set. Now, for the early retired ones those are very rare and people will pay 25+ to finish the set, e.g. Aeon, Tailspin etc...
Lilimu, although retired, has giving out her sash on numerous occasions so should fall in the 3-5 mil range for now. However don't forget all things raise with UO inflation along with other rare items. A bottle of green hair dye that anyone could get during the first Clean-Up Britania for a mere 30k is now fetching 10 mil.