The 4 digit rule on the market is great because it means every relist is a significant change in price from the previous order.
However there is an issue with the implementation. When the first significant digit is a 1 the relative change in price is way bigger than when the first significant number is a 9. The difference is almost a factor 10.
For example A good is listed at 1001 isk. The next possible step is 1000 isk which is a 0.1% decrease in price. This is a fine amount and repeated relisting will quickly drive the price to its equilibrium.
However when something is priced at 9999 isk the next possible step is 9998 isk, which is only a 0.01% change.
The above means prices move way slower in certain price ranges than in others, which limits the usefulness of the feature.
Solution: Tweak the minimum step to always be around 0.1% by looking at the first digit. multiply the minimum step by this first digit. This means at 9999 isk the next possible step is 9990 isk, which is a 0.09% difference and way closer to the 0.1%.
When the 4 digit rule brings markets to their true equilibrium point the relist fee becomes obsolete.
The 4 digit rule is easy to implement and, coupled with the relist fee, solves the micromanagement problem. In the .01 days, the percentage change varied depending on the price of the product - why should it matter now?
0.01 isk is not a significant amount for the vast majority of orders. The difference between 0.00001% and 0.0000001% doesn’t matter, the difference between 0.1% and 0.01% does.
I think it’s fine as is. More expensive items have higher relist costs, so it all balances out – you can make smaller % changes, but it’s expensive.
Besides, how would you implement a %-based minimum in a way that was quick and easy for market users to calculate? “Let’s see, price is 9999. 0.1% of that is 9.99. Which way does that round? Okay, let’s say 10. So the new minimum price is 10009. Got it. Now for the next 100 orders I have to update…”
Sure it rounds itself, but traders still need to know what number to enter to avoid being rounded badly.
Right now, for instance, if the top buy order is priced at 200,000 and I enter a buy order for 200,099, the system will round me down to 200,000. I have to know that I need to set my price at least at 200,100 in order to become the top order.
WIth four significant digits, I can do that math easily in my head. With a percentage-based system, I can’t. Users will routinely either find themselves rounded down and not being the top order, or raising their price more than necessary.