Store up to 5 GB in Google Drive, 1 GB in Picasa, and 10 GB in Gmail for free and pay for additional storage as your accounts grow. Here's how it works:
Tap into your free storage as soon as you start using Google Drive, Picasa or Gmail.
Purchase additional storage that can be shared across Google Drive and Picasa (free storage doesn't transfer across products). When you purchase additional storage, your Gmail storage limit will automatically be increased to 25 GB.
Using Google Drive with a Google Apps account? If so, you can purchase additional storage. Gmail storage won't change when you purchase a Google storage plan with a Google Apps account.
Note: If your administrator disables either Google Drive or Picasa Web Albums for your domain, you won't be able to use purchased storage in these services.
Google storage plans
Choose from the following monthly Google storage plans to be used with Google Drive and Picasa. When you purchase one of these plans, your Gmail storage limit will automatically increase to 25 GB. Yearly plans aren't currently available.
Storage Monthly Rate
25 GB $2.49
100 GB $4.99
200 GB $9.99
400 GB $19.99
1 TB $49.99
2 TB $99.99
4 TB $199.99
8 TB $399.99
16 TB $799.99
Source: Click Here