Wow... that stuff is expensive! I don't know what I paid for mine, but at 1/8" and 3 ounces, there's not a lot of silver there.
I bought it for some plumbing projects many years ago, and I still have plenty left.
That said, I don't know why regular "lead/tin" solder couldn't be used for this. According to the Web, Pb/Sn solder can bond to stainless steel if a strong flux is used to overcome the oxide barrier layer (same applies to silver solder). Sn (tin) may also have an adverse effect on stainless steel, but this would probably be negligible on cable ends.