Are you referring to the tournament at Pebble Beach? Celebrities aren't paid to play. They play because they love the format and the ability to play those three courses.
They pay to play in those tournaments. Pebble beach requires an invitation and at least $25,000. That was the fee a few years back. It's probably more now. It is the most expensive and most unique. You play three courses and the top 25 or so play on Sunday too. Most other PGA events have one or two day pro am play and you can play if you have a USGA handicap and cash. I think most run 5k to 15K.
They have played together before. http://americancenturychampionship....e/american-century-championship-2011-results/
Tony Romo received a sponsors exemption and will play in the Byron Nelson tournament on his home course in May. It will be interesting to see if he makes the cut.