I know it is not a book and doesn't go with the gift certificates. But a method I have been using is to get books into my Oreilly's books shelf and if I find I use the book for more than a few months I buy it.

On MySQL I recommend MySQL Cookbook and Managing and Using MySQL, 2nd Edition. For Perl side I would suggest using the safari option to get an idea of what you want and what you will use. But than you may notice I am a big O'Reilly fan. ;)