I think for any barbell exercise, there is almost always a dumbell substitute. I'm sure someone could help you with that.
As for the stability ball, they are super cheap at Walmart. I'd offer to ship you one of my extras, but if you paid the postage it would probably be more expensive than buying one new (I think?). I have an extra one at home.
Definitely worth the investment, but again, there are always modifications for those few exercises that are using a stability ball. Don't let that stop you! Go for it!
I'm in the mood to spend other people's money today!!!
hehe
:+
Punky-meister