For anyone who is looking for a Vectrex multicart, the folks from Retro Towers are now selling the 72-game multicart for they system (note that it is a PCB-only version). 

Here is a demo of the cart in action:

Vectrex 72 game multicart video demonstration[/align:29leymhk]

Here is the description for their site:

The Vectrex 72 game Multicart include 72 different games for the Vectrex. There are no copyright issues with this product, because the company that created the vectrex put entire game library in the public domain.

The games included are some prototypes, demos, homebrew games and all the games ever released for the vectrex with the exception of Animaction.

Features
 

• Supports 72 games

Note: Some games will require the light pen, 3D imager or the spinnter controller to work.
   

• Simple looking operating system, so it is very easy to find the game you want to play.
• Pushing reset button will load the same game, so no need to choose the game again if you push the reset button.
• The operating system has pleasant music.
• PCB version comes with an anti static bag to keep it safe.

More details can be found here:  Vectrex 72 game multicart - plays homebrew and full games.