Why do you think a $75-150 pot is overpriced? I agree that might be the case for a simple thrown pot that is less than 10" (25 cm) in diameter, but for anything beyond that it allows the potter to make a living.
I am a decent potter, although not in very good practice due to work (that changes in July). I figure that if I went into production mode where I was making 10+ similar pots, I could throw, trim, fire, glaze, and glaze fire simple round pot with about 1 - 1.5 hours of touch time. A professional potter can probably cut that in half since they are more proficient and have a better organized workspace. The materials for such a pot are not that expensive and you can fire quite a few of them in a kiln load so that will put the materials and supplies in the $10 range. You then have to factor in loss during firing - 10% for such simple pots is probably about right. How much is the potter’s time worth? They have lots of years of experience so I am thinking a minimum of $30/hr and $40+ is probably more like it. Now you have a direct cost of $25-$35 without any allowance for overhead like building heat and making sure all fo the clay and other supplies are in stock.
Now you would like a larger pot - the time, materials, and failure rate increase faster than the size - probably at least the square of the size. Oh and it should be an oval or rectangle - the time probably at least doubled for the same size pot (my time increase is much higher, but I am just getting started on those). Keep in mind that these times are all for production pots - not custom pots where the time, effort, and failure rate increase even more.
Affordable bonsai pots of any size are most likely going to be mass produced in China or another country with a low labor rate. They may be slip cast (high production) or for a little more money pressed into a mold. However, now you have to include shipping (and the loss during shipping), import fees, and other taxes (trade wars don’t help).
Sorry about the rant, but I feel that many folks don’t understand the time and effort it takes to make decent pots. If there are any professional potters who want to correct my estimates I would love to hear from you.