Here's a link to a bulletin board software program loaded with features. I haven't used it, but it appears to be pretty well designed and has a low price.
You will need your own server or a web hosting site that will allow you to run it. Check the requirements and features to see if it meets your needs.
BTW, I found it and many others using a google search on the term 'bulletin board'. (Just ignore the office supply hits or use advanced search & exclude them.)
You need to provide the link when you offer one.