Yeah, you could still make your own, if you dug into the installer app and found the source DMG that it boots to for the install, and restored that to a USB stick with Disk Utility, or the command-line asr tool.
In fact, I used their InstallESD.dmg as a template for how to make a lightweight bootable removable drive for system imaging at my company. I have a 5GB USB stick image that contains the payload OS (10.8.5) as well as the installation packages for our required antivirus, data-at-rest encryption agent for laptops, software delivery agent, Java, the tool we use to connect to Active Directory, and a few scripts that name the machine properly and set up the network locations depending on what subnet it's on. Time from go button to login against AD? Around 8 minutes if you're on a solid state disk.
Works on USB, FireWire, and Thunderbolt.