can I create a .deb file from an already installed package?

[valerian <valerian@bellsouth.net>]

I wanted to install libbusiness-onlinepayment-authorizenet-perl, but
when I run apt-get, it says:

Package libbusiness-onlinepayment-authorizenet-perl has no available
version, but exists in the database.
This typically means that the package was mentioned in a dependency and
never uploaded, has been obsoleted or is not available with the contents
of sources.list

A little while ago, I had already installed that package on another machine
(also running Debian 3.0), but alas the .deb is no longer in
/var/cache/apt/archives, so I can't just copy it to the new machine. :(

Is there a way to reconstruct a .deb file from an already installed
package?

On another note, is there an easy way to create .deb files of Perl
modules?  I don't like using CPAN very much because it tends to install
files all over the place instead of just /usr/local/lib/site_perl...