Looking at the picture of the front of the lens, it looks like there's a lot of scratches/cleaning marks. However you mention there's no damage to the surfaces. Are those scratches on the diaphragm blades or something else?
If those are in the glass, they're just a bit too numerous/deep for my taste, but considering your asking price, I suspect someone would be willing to accept them. If the glass is in fact undamaged, I'd consider the lens.
Do you have any pictures showing the "flashlight test"? -- fully open aperture, strong flashlight shining into lens from rear and photo taken of the front, at an angle from the axis of the lens. This usually shows any/all stuff of concern, such as scratches, fog/haze, fungus, dust. Saavy lens people won't freak out if there's some stuff in there. There usually is. Also, another picture of the "flashlight test" from the other end would be useful (shine light into front, take picture of rear).