Q: Wallstreet M4753 Mouse Type

atari,

The Wallstreet has what are now called legacy ports...SCSI, serial, and ADB.

SCSI is a high speed interface now supplanted by USB 2.0 and FireWire.

Serial is a low-speed port used for serial printers, modems, and other devices.

ADB (Apple Desktop Bus) is used for mice, keyboards, and a few other devices.

Since the Wallstreet does not natively support USB or FireWire, you will need to find an older ADB mouse. Kensington still makes one, the ADB/USB Mouse In a Box, M64475, as is now an optical mouse. It uses a small connector that converts the standard USB connector on the mouse's cable to the ADB connector.
http://us.kensington.com/html/6389.html

There are probably many of these ADB mice for sale on eBay for just a few dollars but they probably have the older trackball instead of the newer optical system.

jpl is on the right track for new mice.

If you decide to get an old one, ANY ADB mouse will work. There are earlier ones that have an angular look, and later ones that have a more teardrop shape. Apple uses a removable ring on the bottom that allows the mouse ball to be removed and cleaned.

You can also use any ADB keyboard, if you need to do a lot of typing and you grow weary of the WallStreet keyboard. The mouse can be plugged into a port on the keyboard so that both can be used at the same time. All Apple ADB keyboards have the connector for another device, in the end, on the top, or underneath.

The ADB connector resembles a round S-Video connector, but it has only 4 pins and a plastic alignment pin.