If the data that you need is fairly simple- for example names and addresses, account details etc- then there are a number of free tools and websites etc that you can use to create data.
My favourite at the moment is http://www.generatedata.com. It can create data in a number of common formats such as XML, CSV etc. I have found it to be a good companion to automated testing tools such as JMeter, HP UFT, LoadRunner, and service virtualisation tools.