You can use my email address firstname.lastname@example.org to contact me.
Please do not ask about the value of a camera. Just search eBay for a while and you probably will get a good idea about the value of your camera.
I will gladly help you to identify an early camera, but please send a picture of your camera. Also I will try to answer questions about the history of a camera or the way it worked.
If you ask me to invest time in your question, please be prepared to do me a small favor in return, like downloading a page from a journal in the Hathi Trust database. Many old photographic journals can be found there, but often they are only available in the USA. I will probably never ask, so don't worry too much ;)