My preferred tools are Java (and particularly JSP and Servlets) sprinkled with deliberate amounts of CSS, XML and XSLT.
Of course driven by a powerful database engine (any will do that you have access to and has a decent JDBC driver available).
If I'd have to work on an all free basis (heck, I've done just that...):
- Tomcat (or Orion if it's a non-commercial project)
- Firebird (open source version of Borland Interbase, which is an extremely powerful database and far superior to mySQL in both stability/speed and scalability)
- Xerces and Xalan for XML/XSLT processing
- maybe a framework like Struts (or roll your own, depending on your skills, needs, etc.).
all this will run on a PC
driven by Windows or Linux no problem, but can scale easily to Solaris or HP
The most expensive I've been involved with so far:
- Silverstream 3.7.5 app server
- Silverstream portal server 1.2
- Oracle 8i
- 2 HP
-9000N series servers to run it all
That's about a million Euro to run a website (compared to maybe a thousand for the cheapest solution).