airbag light won't turn off- $572 for a cable sounds kinda steep, no?

[yoshhash]

I have an airbag indicator light that won't turn off. Similar to this:
http://www.yarisworld.com/forums/showthread.php?t=32554

My Toyota dealership service dept describes the cause as this: B18010 Stored- open squib circuit

they prescribe this correction: require replacement of spiral cable, retail cost $571.76 + tax. I didn't get an estimate for labour cost, but I imagine it's also steep, it's housed within the steering column.

I find this extraordinarily expensive for a cable. Even if I bit the bullet and got it done, how do I know it won't require replacing 6 months from now?

They tell me it could affect the performance. Being a safety issue, I know better than to cheap out on it, but my bullshit meter is going off loudly.

Any words of advice? Any thoughts on the idea of finding a part from a wrecker and doing it myself?