I have some old thoughts on breeding fish in general & selling bettas. Early on in our fish keeping we had easy breeding CA cichlids & kribensis. Even without trying to raise the fry some survived past parental snack size. We traded the to lfs for store credit; somewhere between 1/4 & 1/3 of what they could sell them for. Great! Until they still had a tank of now larger junior size fry & would no longer take them even for free. We were regulars at our 4 shops & took road trips to more distant 1s. Our fry were fish non grata after a while, lol & there were never 200+ fry!
I don't belong to my local fish club but I've been a few times. A betta splendens breeder had many youngsters (maybe 20-30+) & was selling the larger males for $2, younger 1s & females for $1 after not many bid at the auction part. It's a pretty large club. He had some good-looking fish & I might have been tempted if I had a tank available.
So, in some ways economics & labor comes into the equation. & then there's the culling of less than wonderful perfect fry. That was always very difficult for us even when we had fish big enough to feed them to (sniffle). I'm sure it's different for much more rare fish than we had
I'm very glad we had that experience & the lessons that came along with it. We have fish breed casually now & are always thrilled to have fry show up but only have a few that survive (except maybe bn plecos, lol). If I wanted to tear down my river tank to catch hillstream fry, a lfs will buy them. But that's not in my near future. My 1-4 sewellia fry/year are enough to slightly more than replace any aged out adults, just right!!
So, my advice is to enjoy the experience in your way of doing it & think twice before doing it again!