I’m looking for a script (PHP/MySQL) to handle support questions – preferable free or cheap – any good solutions?
There are many many open source support scripts and the best is kayako support. see this: http://best-php-scripts.com/faq_scripts.htm
Yup, I would definitely go with Kayako. If, however, you prefer open-source or free scripts, I would highly recommend HotScripts. Choose a high rated one, there are dozens: http://www.hotscripts.com/category/php/scripts-programs/customer-support/