finding MARC data: Net::Z3950 might help http://search.cpan.org/~mirk/Net-Z3950-0.50/Z3950.pm

databases you might search with NET::Z3950
get a list from here
http://www.indexdata.dk/targettest/l.php

finding book data: Net::Amazon might help

I do recoment Koha (www.koha.org) : last time I checked it was written in Perl, used HTML::Template, could import MARC records, and, most important, it was used in real life ... the only drawback was that it was overkill for the research library I worked for ...