I don't know enough about bettas to determine quality of those (although I think they look beautiful). Coming out of horses, I can say there really is no such thing as "asking too much". The price of an animal is based on what the seller feels they can let that animal go for, not necessarily what they feel others will pay for them. If they price them high, they are wanting to keep them, but willing to let them go for the right price. For example, my show gelding that we had bred we priced at twice what we had paid for my multi-National Grand Champion show gelding who was extremely well known in our industry. We didn't expect anyone would pay that for him, especially when you could get a seasoned Champion for less. But, to our surprise someone wanted him bad enough to pay it, and it was what we felt we could let him go for.
This happens in horse auctions too. A person will put a high priced horse (one they don't really want to sell, but are willing to let go for a high price) through the sale to see how it does and what type of interest they get for their other horses.