Tripod extender, existence and obtaining of

[CorisCapnSkip]

Is there such a thing, and where can I get one? I need something I can attach to my tripod where the camera is usually screwed on, with two other screws so I can put two cameras on the same tripod at once. Does such a thing exist? What is the name of it so I'll know what to search for? Thanks.

[CorisCapnSkip]

Oh, here's one: http://www.amazon.com/Gitzo-G1584-Double-Camera-Platform/dp/B0002Q72RQ

Here's another: http://www.amazon.com/Bogen-Manfrotto-Double-Support-Platform/dp/B0000AE65U/ref=sr_1_1/103-0761335-2448647?ie=UTF8&s=electronics&qid=1191302023&sr=1-1

If anyone knows of anything like this for less, please advise, thanks.