sick coral
You can't reliably buy in bulk as the price changes prevent that. Additionally request orders are a thing. You can buy dozens at a time that way. And if you're buying matches up with a sell order of similar price, it'll auto fill by matching them together.
waxen skiff
A 'click and hold' option has been suggested a few times. I suggested in a previous thread that they could have it cancel purchasing if the price changes, and the player can click and hold again if they're okay with the current price.
loud sorrel
its impossible