I've got a 15" AP Dovetail Plate (DOVE15) and the 15" Sliding Bar (SB1500) that I'm not going to need. These are in very nice shape, and I'd be happy to supply photos of them if you are interested. New these cost $95 and $45 respectively.
If you want them both, I'd let them go for $95 including shipping. If you just want the Dovetail Plate I'd sell that for $70 incuding shipping (the sliding bar has been spoken for - if these don't sell as a set)
Thanks for looking!