You can buy Yukon aftermarket axles (or Dr. Diff's own house brand axles) for ~$200.00 shipped brand new so I don't think $100.00 is so cheap it should send up red flags.
Even if they are re-drilled originals or re-splined C-body axles $100.00 is worth it and a small price to pay to have the convenience of the BBP.
Like anything else you buy used or even new make sure you check them over good.
If that were the case I wouldn't own anything!
People that wave that flag usually are the ones that have been bured because they didn't ask the right questions, do enough fact checking, or just plain didn't pay enough attention to what they were buiying.
If you decided to pass them up let somebody on here have a chance at them.
I could use a couple more pairs and I'm sure others would be interested for that price as long as they are useable.