I doubt it will go quite that high like things were doing during the peak of COVID, but if you aren't in need of an immediate sale, no harm in starting it there. I think it would sell for sure for $5,000 so if you are in need of an immediate sale, set it at that. Personally, I'd set it a little lower than that, with a 14 day run time and no Buy It Now option. Let the market dictate what it will bring. Sometimes bidders will get into a bidding war and things will go for well above what they're worth. I'd maybe be interested if I didn't already have one in same condition. If the money I have saved wasn't already earmarked for a SPAS-15, I'd be tempted to get a second 11711. Those SPAS-15's don't come up for sale very often at all. So, when they do, I have to be ready. 🙂
Gunbroker will give you great exposure. I buy most of my stuff there because I like odd, unusual, and rare stuff like this.
The reason you can't PM the other person is because you have to have so many posts before you can. I believe it is 5 posts. So, just be active on the forum. Not implying you would, but don't post junk just to get your post count up or admins will block your account. You could start by replying to that thread you are talking about.