The miniseries angle could work. Each season covering a decade of the show’s run from 1972 to 2017. I agree, Bill Murray could make a great Bob. Your guess as to who’d play the syndie hosts.
FWIW, the miniseries as proposed would focus mainly on the Barker and Carey series. I've broken them down into parts, with the following actors and their roles:
PART 1 (1972-1986)
Jim Parsons as Bob Barker
Ben Stiller as Johnny Olson
Wayne Knight as Rod Roddy
Courteney Cox as Anitra Ford
Anna Faris as Janice Pennington
Brittany Daniel as Dian Parkinson
Sara Gilbert as Holly Hallstrom
Diedrich Bader as Roger Dobkowitz
Leah Remini as Kathy "Fingers" Greco
Jon Cryer as Mark Goodson
Jim Belushi as Bill Todman
Max Greenfield as Bud Grant
Dave Foley as Marc Breslow
PART 2 (1987-2003)
Jim Parsons as Bob Barker
Wayne Knight as Rod Roddy
Anna Faris as Janice Pennington
Brittany Daniel as Dian Parkinson
Sara Gilbert as Holly Hallstrom
Diedrich Bader as Roger Dobkowitz
Leah Remini as Kathy "Fingers" Greco
Keke Palmer as Kathleen Bradley
Zoe Saldana as Claudia Jordan
John Goodman as Paul Alter
Colin Mochrie as Bart Eskander
Extra as Nikki Ziering
Extra as Heather Kozar
PART 3 (2004-now)
Jim Parsons as Bob Barker
Diedrich Bader as Roger Dobkowitz
Leah Remini as Kathy "Fingers" Greco
Ashton Kutcher as Rich Fields
Beth Behrs as Rachel Reynolds
Ariel Winter as Brandi Sherwood
Amber Stevens West as Gwendolyn Osborne-Smith
Tiffany Haddish as Lanisha Cole
Tia Mowry as Phire Dawson
Kevin James as Drew Carey
Woody Harrelson as Mike Richards
Kristen Bell as Amber Lancaster
Yara Shahidi as Manuela Arbelaez
Neil Patrick Harris as George Gray
Frankie Muniz as Rob Wilson
Justin Timberlake as James O'Halloran
Stephen Curry as Devin Goda
Colin Mochrie as Bart Eskander
Dylan McDermott as Rich DiPirro
Sean Giambrone as Scott Robinson
Nina Dobrev as Hope Vinitsky (Mighty Sound Effects Lady)
Adam Sandler (actor) as Adam Sandler (director)
Extra as Gabrielle Tuite
Extra as Tamiko Nash
Extra as Shane LaLonde
For all three parts, Dan Aykroyd as Stan Blits would serve as the narrator.