@EverythingDucks Glad it worked out for you.
Not that this will work all the time, but I've gotten rid of drakes by explaining (in the ad) that people (or their children) in the city that might want ducks as pets want drakes. Just as city folk dislike roosters, female ducks are as loud. Drakes are nice and quiet and multiples can be kept together fine as long as there isn't a female around.
I'd also look at Craigslist and Marketplace, people in your FB group are more likely facing the same problem and not your prime customers.
I feel your pain, breeding leads to many headaches, and 100+ degrees every day since May(!) has even made eggs not worth shipping. My feed store has two brooders packed with weeks old chicks and guineas; apparently, no one's buying either. I'm growing out in the hopes that fall/winter is a better market, hopefully at least for layers.
Agreed, and if they're young and flock mates, a separate pen will work for a while, but maybe not for long. I didn't have enough pens to separate males by breed, so the spare Spitzes, Ameraucana, and eggers all went in together. A 10x20 pen for 12 roosters and full-size cockerels. They ran together during the winter, so they weren't unfamiliar with each other, but eventually the stress of males penned together caused some to just drop dead. Wouldn't you know it, it was my spare chamois Spitz, self blue Ameraucana, and OE, and the lowest pecking order blue egger (I think he was actually killed by another rooster). Basically, two of each variety saved for breeding went in, only one of each came out, except for the chamois, 3 went in, 2 survived but....
To continue, the best chamois Spitz became a manfighter because of all this. The rest get along fine. My mistake was thinking that I wanted to keep my hens happy by letting them free range since the bobcat had been taken care of. Until they started disappearing because multiple other predators eventually took its place, and AI became a threat so everyone went into pens. Khan (the bad chamois) was mean to the hens in the breeding pen, so Ricardo Montalban (the good chamois, but less to standard) took his place. Now that we're clear of AI, the hens, pullets, and unsexed teenagers remain penned and have a run, the roosters I want to breed are in breeding tractors, and the other roos are free to roam. Of course, apparently even the predators don't want roosters, because no ducks or roos have gone missing in months.

(I'm certain it's because the creek and tank have dried up and they're just not hanging out here, they'll be back eventually.)
I've got about 50 chicks on the yard and 60ish going into lockdown today, so I'll be going through all of this again in a few months. Breeders will stay penned, extras will go in the winter yard and be able to free range the whole property. Predators will take care of some, I may be able to sell some egger hens, and I have a small group of friends that might be interested in a processing day...that's the story I'm convincing myself of for now.
Really? There's one down the road that I've been thinking of asking to help me do a processing day, but I haven't bought all the equipment yet. I figured they couldn't do chickens at their place because of TDA rules (i.e., they're only authorized for game species), but I haven't actually asked. Guess I need to get out and meet some new neighbors.