i use the opti-pac in my box for both my spinner and my tracball ( oscar spinner and 4" ball out of a missle command ) , basicly , if you dont touch either for about 5 seconds it goes into a wait state .. the first one you touch takes control of the mouse pointer , during this time the other one is disabled ...
their is a way to get both to work in 2k/xp by useing analogmame , but that doesnt help with other emulators.
and the 69.99 is worth it , i got really really lucky and found a place neer me that happen to have one , but the effort involved in looking on e-bay etc ( i was even looking at bochi balls at one point ) is a major pain.