This suggestion will annoy some people for getting a notification without content, but it has benefits, so hear me out. Allow a single post on content threads to announce when a creator is running a sale. Maybe have it include the price and expiration date, and possibly with a strict stipulation that it must be deleted when the sale is over.
It would help the forum because the heroes would sub and get more content for the community. It also would potentially bump some lesser-known or forgotten creators, many with little to no content, and introduce community members to creators they may have never heard of before that they would enjoy. It would also help the creators themselves with the added subs, serving as an advertisement.
I came up with this because I have a long list of past subs on OF and I get a notification every time any of them run a sale. I looked many of them up to find graveyard threads, or sometimes no thread at all, and I think this could change that. I know you guys are also worried about clutter, and no doubt this would add to that with people not deleting the sales, but I think the pros outweigh the cons on this one.