Here are the Details:
With these changes, a 24x7 Extra Small Compute instance with a 100MB SQL Azure DB costs less than $20 per month. The price of compute and storage continues to be consistent across all datacenters and Pay-As-You-Go customers will automatically see the reduced prices reflected (as of today) on their next bill; there is no action required.
More detail here.
On February 14, 2012 we announced significant price reductions and a new entry level database option to meet customer needs on both ends of the database spectrum. Be sure to check out our pricing calculator and pricing page for additional details.
SQL Azure Database is billed based on a graduated rate based on the size of the database. It is available in two editions: Web and Business. The Web Edition supports up to a 5 GB maximum T-SQL based relational database. The Business Edition supports up to a 150 GB maximum size T-SQL-based relational database.
Database Size Price Per Database Per Month
We charge at a monthly rate for each SQL Azure database you utilize, but we amortize that database fee over the month and calculate your fee on a daily basis. For databases greater than 1 GB, you will be billed in the next whole gigabyte increment. For example, if you utilized two Business Edition databases, one that was 4.4 GB and one that was 14.4 GB for 1 day during a billing month, you would be charged for a 5 GB and 15 GB database for that day, which would total $2.643. Below are the calculations: