I signed up to Bed Bath N Table's newsletter last week and got an email advertising their autumn sale today. It runs until the 23rd of April 2017.
Found this Mr Fox sheet set which I thought was really fun and perfect for little boys - the single sheet set is on sale for just $55.95, which isn't a bad price if you compare it to Amara, who sells the duvet cover of this series on its own for $87.
The single sheet set includes a flat sheet 180 x 250 cm + fitted sheet 91 x 193 x 37 cm + 1 pillowcase 48 x 73 cm.
Delivery is an extra $15 on all orders below $150, but you'll find plenty of good value items on sale in the bed, bath, table and homewares categories if you want to reach that threshold.