Rockler Lazy Susans.
By MikeJ

Heavy Duty Lazy Susan for the donut
Solidly built lazy susan provides stable support for large stationary platforms. Ball bearings ensures smooth, quiet movement. 17 ½''diameter. 330 pound load rating.

Rockler Tech Sheet 12451.pdf

Part No. 12451
Price  $55.99

Click here to find this online from Rockler woodworking products.

DennisW found a cheaper source for the exact same part.  (Thanks to the R2 Builders Club!)
At you can purchase an absolutely identical lazy suzan to the rockler:
17-3/8" Lazy Susan Bearing 12K68.17 $ 43.20

Low Profile Lazy Susan's for the collar
Precision ball bearing system delivers years of quiet operation and extremely smooth rotations at the touch of a finger. Recessing drops this 5/16'' thick hardware to barely visible 1/8'' profile. Rust resistant zinc plating.

9'' Round Lazy Susan (non costume version)
Rockler Tech Sheet 18531.pdf
Part No. 18531
Price  $4.99

12'' Round Lazy Susan (costume version)
Rockler Tech Sheet 28985.pdf
Part No. 28985
Price  $6.29

Click here to find these online from Rockler woodworking products.