I have a OEM  accessory C-10 backrest with luggage rack.
Very good used condition. 
No rips or tears on pad, and bracket appears to be repainted - looks good.
Hard to find.
$125.00 + shipping

Another pic.

These things used to sell quick (same day almost).  I got one to sell too as soon as yours does.  Good luck with your sale.

What weight will this rack hold??

What weight will this rack hold??

OEM says 5 pounds.  Many have carried around 20 pounds with no adverse issues.  Add an additional support bracket on each side and it can easily do it.  At some point you become more limited by the rear sub-frame.

I used to put 60#s of barbell weights on mine when changing the front tire. Never thought twice about it.
Wayne

What weight will this rack hold??

Sold, pending payment.