You're welcome.  I suspect that the folks who can answer
your question (I'm not one of them) now have enough info.*
to start formulating answers.

Hope you find what you need..

* And if they don't, perhaps they should say so!

300 page hits a day is trivial.  Virtually any tech stack can handle
that.

20 - 30 users at one time is a bit more exciting, especially if they hit
it all at once.

I would suggest you put together a mockup HTML page of a 'typical' user
session.  For example, the 'get all stocks starting with Z' query, might
be a good start.

Then, figure out how many db queries this would take to answer.  Say,
two hundred, generating a two hundred row table.  Bang together a
screenshot of same, so you have a sorta-spec.

Finally, decide the longest wait you are willing to suffer through if 45
(half again your worst case) hit it at the exact same time.  Half a
second?  Ten seconds?

With this together, you can put together something really easy, like a
simple JSP/Struts app that pushes back something of roughly the same
size, based on a query that always returns the same results.  This
should take less than a day to put together.

Time it, with something like JMeter or the like.

Frankly, with only a few hundred hits a day, and loose requirements on
your 45 hits, you can use just about anything.  I would probably use
Tapestry and Hibernate, but JSP/Struts, or Ruby on Rails, or Mason in
Perl would work, depending on what your team either knows or wants to
learn.

Scott
--
scott@alodar.nospamtome.com
Java, Cocoa, and database consulting for the life sciences
Life is too short for bad software