A good way to make a do-it-yourself script is to record an episode of a game show (let's say Price, in this case) and transcribe it in Microsoft Word. Daniel Rosen, if nothing else, doesn't seem to deviate from the script, so you can transcribe from him word-for-word without much fear of capturing any sort of ad-libs.
Split all of your pages into two columns and leave one column blank. This is where the director makes his markings on his own copy of the script. Most scripts have the copy on the left side of the page and leave the right side blank - some have this flipped.
Put each element of the show on a separate page. Show open on the first page, first One Bid on the next page, prizes for the first stage game on the next page, etc. Double-space everything so you can make notes on pronunciation, emphasis, etc. Make sure your text is ALL CAPS so that it is easier to read, and choose an easy-to-read font (Arial 10 or 12 point works fine for me).
Once you're finished transcribing the text, print it out, read it through, make notes, read it through some more, make notes... Once you're comfortable enough, start asking your friends to listen to you. Those who have some knowledge about TV and radio announcing can give you some valuable pointers, but those who don't can also be valuable for their gut reaction to your overall style.
