Update – Offer has ended
For those who use the basic version of Dropbox (the 2GB version) or who are considering opening an account, Amazon has a deal you want to look at. As part of Amazon Prime Day, the 1TB version of Dropbox Plus is $80 for 1 year. The account is usually $99, but with Prime Day you get 20% off the price. Deal Alert: Dropbox Plus via Prime Day 
The following chart will show you the difference between Dropbox Basic (Free Version) and Dropbox Plus.
Source
- Amazon Prime Day – Dropbox Plus 1 TB Deal