For my recent build I grabbed a 2 1/2" hole saw from Napa. It was fairly inexpensive and made quick work of the job. Added bonus is I now have the tool for future builds!
Not a typical UDS build by any means but you can see what I did...
WSM 22.5", One-Touch 22.5", Redhead 18.5" Smoke Joe Silver, Q200, "Mr. T"