As you are probably aware, Microsoft are increasing their prices in 2017.
However, because many of these services are price-protected for the term of a 12-month subscription, this price-change will only be realised at renewal. For example, if you have previously added a new Office 365 subscription in November 2016, the price will remain the same until November 2017, after which the price for the subscription will then increase in line with current levels.
Take advantage of this and take out your Office 365 for Business 12 month subscription (but payable monthly!) before 31st December 2017