It can be hard to get an ST mous these days. But....
It IS possibble to connect an serial PC mouse to your ST.
This is what you need:
- a serial PC mouse (aprox. $8,-)
- a RS232 port converter 25p male to 9 pins female (aprox $10,-)
- a driverprogram, which I can mail to you if you want. this program can also be fount on the internet but i can't remember where (freeware)