Official stance from a forum moderator / official answer from the site owners is: Yes and No.
You can't sell DIRECT from here, simply because it creates too many headaches and puts the forum in a tricky situation should a transaction have issues. However you are more than welcome to pop a link in your signature (see here:
https://www.thekennel.net.au/forum/index.php?account/signature) to an ebay / Gumtree link for an item you are selling.
Please don't create a new thread for it, but by contributing to the site by way of posts posters will see your signature and the link to your memorabilia, and engage you if interested in purchasing it.
By taking this approach it encourages people to contribute to the site (rather than just a dump and run), and also detracts people signing up to post fake merchandise.
Hope that makes sense.
...
On the topic of memorabilia, if it's signed, then ideally it should have a Certificate of Authenticity or proof of signature. This increases the value of such items.
In all honesty though I've been around here over a decade and in that entire time can count on one hand the number of items sold here.. we may have lots of members, but it may not be the target market to sell memorabilia too.
!!!!!! SIDE NOTE !!!!!!
Special consideration may be given in the instance the item/s is being offered for sale for a charitable purpose. If this is the case please contact a moderator for discussion.