Karen -
I can see how these things accumulate! We don't allow buying/selling on the forum, as that is what the Marketplace link at the top of the page is used for. If other members have some ideas of costs, that's fine, but any other transactions should be offline. IBMWR has a section for selling things...you could check them out for the Vintage stuff to get an idea of costs or put something there for sale. The Vintage BMW club also has a forum where there are likely a bigger collection of vintage bike owners. Check out
https://vintagebmw.org/forum/. It is free to join and we try and keep the buying/selling down on the main forum. There is a member's only section where there is a good bit of for sale stuff...it's nice to deal with someone you know is a full enthusiast if they are a member. Check out the various subscription levels for that.
As for a price on the Wixom fairing, my guess would be $200 or so, maybe somewhat higher if someone wanted to use the lower portion. Those are rarer and someone would really want to go that route to look to use those. You might want to put some pictures here just to help those give you better estimates for what they might go for.