If you've got an extra box lying around, install Red Hat Linux 7.2 on it. During the install, make sure to specify all of the options for PHP and MySQL, and install Apache as well. Works like a charm. Very simple setup process.
If not, then ~$10 isn't really that much to pay. You can always sell advertising to help offset the cost (though admittedly the adv. market is crap as of late).