You can try contacting customer service. I know some have had luck with that, others not so much. Although, sinces it's the same price at Kobo you can get it there and sideload it.
Rainshadow Road by Lisa Kleypas St. Martin Press is $2.99 at Amazon and Kobo. $9.99 here at B&N. Don't they get notified about price changes?
This happened recently with another agency book. It seems B&N does not adjust prices in the weekend.
The price will probably be adjusted on monday.