Pricing depends on many factors: how long the species has been in cultivation, how much demand there is for it, how difficult it is to propagate by tissue culture, how difficult it is to cultivate, and how much the stock cost. Selling plants is not just a matter of getting some seed and growing. Getting the seed in the first place can be an expensive and sometimes dangerous process. The seller has to recoup their cost base even before they can make a profit.
Hamata is a species reasonably new to cultivation, it is a fantastic looking species and accordingly it is popular. Popularity means people will pay more for it, consequently vendors will charge more for it. Simple market economics. Suddenly dropping the price causes all sorts of consternation, so the price usually decreases over time. That's another thing you're paying for: having it now rather than waiting. If you want a very cheap hamata, I'm sure you'll be able to get one if you wait a few years. Otherwise, if you want one now, you'll have to pay the market price. You can't have your cake an eat it too....
The hybrid sold as species issue raises ethical questions for vendors. In my view, vendors should grow wild collected seed in TC out before selling it on to verify what they're selling. If vendors insist on selling it prior to verifying its authenticity, then they should clearly advise potential buyers that the seed is wild-collected and they can make no warranty in relation to its purity (hey, spot the lawyer).
In this instance, it is even more serious, IMO. The vendor must be aware that their material is a hybrid (and may have been for some time) and continues to sell it as species. Under Australian law, this would get you into trouble for misleading and deceptive conduct.
Malesiana are not the only vendor selling material from wild collected seed. I don't know what the practive of other vendors is in relation to growing out prior to selling, but it might be an idea to find out. In the event they don't, they should have a published policy about what they will do in the event that any plant sold by them as a species turns out to be a hybrid.