There is some misunderstandings regarding to the cost of Jaguar. If you purchased a computer on or after July 17, 2002, you qualify for Apple's up-to-date program if Jaguar was not included in your computer's box for $20:
The above link also lets you purchase a copy of Mac OS 9
CD if you purchased Jaguar as an upgrade to to a Mac OS 8.6 or earlier system that supports Mac OS X for $20.
Computers that come with Jaguar preinstalled or earlier versions of Mac OS X preinstalled come with at least a Mac OS 9 installer on the restore CDs.
Jaguar will let you boot directly into Mac OS 9 or run Mac OS 9 in Classic mode (supports most Mac OS 9 native software except a few Mac OS 9 software products which require hardware access). Preferably you should run Mac OS 9.2.1 or later in Classic mode. To boot directly into Mac OS 9 use the Apple menu's System Settings, and select Startup Disk.
For best compatibility in Classic environment with Jaguar, let Jaguar setup any networking, and use the Mac OS 9 base set in Extensions Manager before running Classic in Jaguar.