Azure is an incredibly powerful service. You can spin up virtual machines, add extra instances of a web site to handle higher traffic loads or create new databases along with a bunch of other options in a few clicks.
It can be easy to forget that adding extra items so easily costs money. Before adding a new item I try to consider the cost before I do so. I do find the documentation around pricing on Azure to be confusing at times.
A common tool that I use and that I keep having to search for is the Azure Pricing Calculator. As the picture below states, the prices may vary but they do provide a good ballpark figure to consider before making a decision.