I can tell you how prices are produced.
Let average crimson price is 35 and there are 15 sellers. Some sellers want to sell fast and put them below average price (30-32), some sellers put them at average price (33-37), some sellers want to get more gold and put them over average (38-40, some seller just don't know prices and put them at "random" price that may be below or over the average price.
So we get: 25,30,31,32,33,34,34,35,36,36,37,38,39,40. Peoples buy cheapest first. so we get 34,34,35,36,36,37,38,39,40. Now the average price is 37, so sellers that want to put them at average price put them at 35-39. And peoples look at prices and buy at 34-37. And so on. Providing that it's a popular item and people have enough gold to buy them.