Zip code woes

Perhaps a bit off topic, but since I'm using them with my Perl script I put it here.

I'm writing a script that takes a zip code provided by a user and looks up the city and state in a Mysql database. This way I can save the user some typing later on by pre-populating city and state fields etc.(I'm so considerate:-).

Well, the script is about done so I went to the U.S.P.S. to get a list of all the zip codes for the US (I was using a dummy list until now). I was surprised to find that they don't provide this for download through their website. You can access their database by looking up one record at a time, but you can't get the list...unless you pay for it.

I thought this was annoying since they need to maintain the database anyway, plus our tax dollars and all...but I figured o.k., how much? $350! Can you believe it!? They sell a two volume hard copy book, same info, for $25. Can you say, 'bend over'!!

Anyway, my griping is done, now here is my question. Does anyone know where I can get such a list (city, state, zip) for the US either free or at a reasonable cost?

Andrew