Here's my idea on how the NPC Store Buyer might play the auctions if it comes in as a seller. This could be shown better in a flow chart but I'm not able to make one at the moment, so I'll try and type it out

- Establish a base price for each commodity, 75% of stock is sold at this price.
- If more than 75% of that rounds stock is purchased then the store bumps up to tier 2 pricing.
- If more than 85% of that rounds stock is purchased then the store bumps up to tier 3 pricing.
- If more than 95% of that rounds stock is purchased then the store might holds its remaining stock for the
next round if demand for the product is likely to be greater the next round.
- If no sales are made when 75% of the time has expired the store will cut its price in half and sell 25% of its stock at a discount. It will then start to step up the price again.
- Base price is adjusted for the next round after production occurs and demand is estimated.
Buying would be a similar process where it is willing to buy a certain amount at a premium price however as its stock fills up it would adjust its buying price downward until it hits a base price at which it will buy any amount. This limitless buying at a base price is justified because it can be assumed in a galactic market that it can always sell anything if it is able to buy cheap enough.