Tiger install DVDs are in short supply. Tiger is no longer available at the Apple Store but may be available for $129 by calling Apple Phone Sales @ 1-800-MY-APPLE (1-800-692-7753). For other sources, do a Google search for MA453Z/A (10.4.6), MA190Z/A (10.4.3) and M9639Z/A (10.4). Also look on eBay. Be sure & buy a retail version (black with silver X) and not a model specific version (gray) (See http://discussions.apple.com/thread.jspa?threadID=1976068 Can I use another Mac's system restore disc on my Mac?.
Possible Alternative if you are currently using Panther 10.3 – Do a Google search for Tiger 10.4 Upgrade DVD . It will upgrade your 10.3 to 10.4, but it doesn’t contain the full retail Tiger installer. Should be cheaper than the retail Tiger install DVD.
After you install the base 10.4.x, update to the final Tiger version 10.4.11. Here's the link for the 10.4.11 combo update http://support.apple.com/kb/TA24901?viewlocale=en_US
Look at this link Mac OS X v10.4 Tiger Installing Software Support Page
You can also download the Tiger Installation and Setup Guide
When you upgrade the OS, do it via Archive & Install. See About the Archive and Install feature http://support.apple.com/kb/HT1710
Be sure to select Preserve Users & Settings. Also, repair permissions before and after the install.
10.4.11 never was released as a PowerPC installer disc. 10.4.6 was the last retail installer disk for 10.4. Apple offers a 10.4.11 combo update to bring Macs up to 10.4.11. You can also use a 10.5 retail installer disk to repair any PowerMac 867 Mhz or faster based on built-in CPU with a built-in or external Firewire DVD drive. 10.4 installer disk must look like and not say Upgrade, Dropin, or OEM, and you must have a Firewire DVD or built-in DVD drive. Also check your PRAM battery is not over 4 years old. If you choose to upgrade to 10.5, see this article: