Board posting guidilines are shown in the "Board Policy
" thread in the "Board Information, Help and Announcements" forum.
As for stating purchase prices, there is no formal guideline on that. But, of course, if one member puts up lots of "Hey, I got this real cheap" messages one after another, this could be taken by some folk as being a bit "cheeky" and likely to reduce their desire to respond (or perhaps increase the desire but in a rather negative manner
In respect of "value" requests, many members will choose not to comment as the Board does not offer a valuation service and any comments that are made will only be the opinion of the poster. And even if backed up with evidence from, for example, previous sales results, any "values" can only be representative of the time they were applicable.