Here is the actual policy stated at neimanmarcus.com : "
Prices are subject to change. Excluding LAST CALL ONLINE CLEARANCE merchandise, we offer a one-time (single order) refund or adjustment for items purchased within 10 days of a price adjustment. This includes permanent Sale items and excludes temporary special promotion items and LAST CALL ONLINE CLEARANCE items. For questions and adjustments call 1-888-888-4757."
I would think that the only challenge you may have is that the b&m neiman stores always claim that they have different inventory and such, but at the end of the day, you just have to remind them that it's the same company!
this is the most explicit policy I've seen. Saks does not have it posted and
Nordstrom is more generic.
What were the 3 bags? did you buy it from one SA? I have found that I am most successful in getting a price adjustment when I have a relationship with the SA and I don't ask them to do anything they would get in trouble for...
http://www.neimanmarcus.com/category/assistance/service/shoppingOnline.jhtml#priceadjustments