Nov 26, 1956 - Sep 6, 1963 (NBC)
    Sep 9, 1963 - Sep 3, 1965 (ABC)
Prime Time:
    Sep 23, 1957 - Sep 6, 1963 (NBC)
    Sep 18, 1963 - Sep 11, 1964 (ABC)  
Players bid on merchandise, trying to come closest to the actual retail price without going over.

The Price Is Right was the most popular and successful show that Bill hosted.  He was as identified with The Price Is Right at the time as Bob Barker and Drew Carey are today. (This as he continued to sit on the panel of the popular I've Got A Secret.)  For two seasons (1959-60 and 1960-61) it was ranked eighth in the Nielsen ratings, and in those years it was, by far, the most watched game show on television.  When the nighttime version began offering Showcases, prize packages that home viewers could compete to win, audience response created an avalanche of more than three and a half million cards and letters a week.  An independent firm had to be hired just to take care of the incoming mail.

The picture below showing Bill with a dog and a model, is almost certainly from an unaired pilot or demonstration episode.  In the series, Bill never sat behind a desk.
Much sport was made in the popular press about the unusual prizes offered to The Price Is Right contestants, and what the contestants eventually did with them.  A Texas farmer once got an elephant as a bonus prize when he was the winning bidder on a grand piano.  Producer Bob Stewart intended it as a joke (the elephant was to supply extra ivory) and planned on giving the contestant a hefty $4,000 cash equivalent instead.  Turned out the guy wanted the pachyderm anyway, and Stewart was forced to fly one in from Kenya.

Among the other off-beat prizes offered on the show over the years: A 16-foot Ferris wheel, a chauffeur driven 1928 Rolls-Royce, a Pacific island, and a live peacock to go along with a color TV (while the show was on NBC, of course).  The program gave away stock in companies, bit parts on TV shows, absurd amounts of food (100 pounds of Swiss cheese, a mile of hot dogs), anything the fertile imagination of Mr. Stewart could envision.

The most unusual contestant ever?  Probably Barney Rubble.  On an episode of The Flintstones entitled Divided We Sail (originally seen April 6, 1962), Barney wins a houseboat (while pretending to be Fred) as a contestant on The Prize Is Priced.  The couples decide to share the boat, and stone-age animated hilarity ensues.

In late 1971, after finding success with What's My Line? and To Tell The Truth in syndication, Goodson and Todman were reportedly talking to Bill about hosting a new version of The Price Is Right.  It's possible that the physical demands of the more elaborate show were too much for Bill, or it's also possible that a decision to tape the show in Los Angeles took him out of the running.  Whatever the reason, the syndicated version ended up being hosted that fall by Dennis James instead.   A CBS daytime version arrived at the same time hosted by Bob Barker.  It's been on the air ever since, hosted these days by Drew Carey.

In perhaps the ultimate indication of the show's place in popular culture, The Price Is Right was the subject of a December, 1959 spoof in Mad Magazine.
Dozens of prime-time episodes exist, as well as a handful of daytime episodes. Most of the surviving episodes aired on GSN: The Network for Games. In addition, four of the twenty-six episodes in a commercially released set celebrating the modern version are classic Cullen episodes.
Adam Nedeff has assembled some fun clips:  
Read two Variety reviews, years apart:
A 1956 review of the original daytime series.
A September 23, 1963 review of the first ABC nighttime show.
There are many pages dedicated to the modern version of TPIR hosted by Bob Barker and Drew Carey.  Fewer for Bill's classic version.
The Price Is Right page at Tim's TV Showcase
The Price Is Right page at Adam Nedeff's Bill Cullen's World
The Price Is Right page on Wikipedia
Home game information at The Game Show Home Game Home Page