If you have a very low budget, PHP and MySQL are both free, open source programs. PHP is a robust server-side scripting language, and MySQL is a pretty capable little database, though it is missing a number of features that SQL Server and Oracle have. The downside of PHP is that it is a more difficult language with a steeper learning curve. It is also more difficult to administer, with patches or enhancements requiring a recompile of the program.
ColdFusion is not free, nor is it open source. It has been around for years now and has been refined to a high level, and the upcoming ColdFusion MX is going to blow everything else away. CF is VERY easy to write and learn, so your productivity is extremely high. CF Studio is an awesome development tool for writing code. You'll hear some folks say that CF is not powerful enough, or not fast enough, or whatever. The reason for this is that it is SO easy to learn CF that you get clueless folks writing 'code' that sucks. While it is very easy to write CF code, it take planning and experience to write GOOD CF code. CF (like PHP) can connect to MySQL or any number of other ODBC data sources. CF also has native drivers for Oracle, DB2, and others.
Client-side scripting is basically JavaScript, and has nothing to do with actually building a web application that runs on an application server like CF or PHP. For this you'll need server-side scripting.
Hope this helps,
Brian
