I wouldn’t extrapolate, though, an entire system based on a few cases in the Gemara.
Primarily, I wanted to answer PBA’s question about how manipulating the market does anything but change who gets the product. The answer is that by “manipulating” the halacha (within acceptable boundaries, obviously), they were able to reduce demand. The threat of doing so was effective at preventing price gauging (so they did actually force the price down).