You can probably find some footage of the Jigsaw puppet on YouTube. Download the footage, record your haunt rules, and use a video editor (Windows Movie Maker works just fine) to sync the puppet with the audio. Don't worry if it looks jerky. Jigsaw's videos are generally jumpy and plagued by static. An amateurish look will actually add to the authenticity.
Either that, or build a jigsaw puppet head yourself and record the video that way. If you do it this way, run some kind of static or old TV video filter over the footage to give it that iconic Jigsaw look.
We did a welcome video at our haunt a couple years ago using a Jigsaw latex mask. We videoed it close in against a black background and moved the mouth with the dialog, trying to turn the head like a puppet might. I was the one wearing the mask. It turned out OK but the video guy never added in any grainy or static effects so it could have been better.
I'm assuming there is cheap/free software out there in the 'net to add video artifacts?
Wanted to add there used to be a guy over on halloweenforum that would do free voice work so we had him record our welcome dialogue. He was absolutely amazing! If I can find the track I'll try to post it.
Audio wise, you can find tutorials on how to do the Jigsaw voice all over the place. The visual quality isn't great on this one, but it seems to be the easiest way. You just need Audacity, a free audio editor.