It would be fairly simple for them to block you, even if you disguise your user agent. However, instead of blocking you, they could simply send back rubbish data to your bot, causing you to make erroneous business decisions.

Writing such a bot is nontrivial and error-prone, but if you choose to do it, there are plenty of methods to do it.

Perl and Python have their own APIs, .NET and Java also have HTTP clients and HTML parsers in them.

Using regular expressions is not recommended as they don't actually work for parsing HTML.

Use a proper HTML parser if you do it.

Mark