With some rare exceptions, most hand thrown gaiwans are made for aesthetic purposes rather than for serious infusion quality. However, good ones do make a difference, especially in longer infusion approaches, such as that for green tea.
Better mould cast ones are so good nowadays that really for 99.9% of users, their full potential has yet to be utilized. In another word, these relatively more affordable factory products serve the purpose well.
On the other hand, there are better ones and not so ideal ones even within the so-called category of mould cast gaiwans. Not all manufacturers understand how a gaiwan functions, esp those so-called international brands. As a tea retailer, I think the best strategy is to focus in those that render better tea taste than more famous brands. There are quite a number of smaller factories and studios in southern Fujian and Chaozhou which productions are very commendable and the infusion effects compare well with good hand thrown gaiwans. They come in very competitive pricing. I think you should source from there.
Back to the pretty hand thrown ones, they do have their social and economic roles, which, unless you already have a clientele which aesthetic requirements and ego needs match the related price range, there should be no rush to offer such luxurious products.
