The point about these slow moving but high profit markets is players that buy the items off the market are not buying because of price - they are buying because they need the item now and will take the price that is listed at the time. In other words, the demand does not change in response to price. These are very price in-elastic items.
This is not fast moving but low profit markets where the aim is to make 2% profits many times over (perfectly good strategy - just not for this blog) and lower prices encourage more buyers.
In this slow moving market, what drives price is supply. If too much supply comes on the market then other sellers will seek to bailout by aggressively making sure they are the lowest price - which has the effect of driving the price lower and faster. However, volumes of sales will remain unchanged.
Take the example below of Nova Heavy Assault Missile Blueprints. This was a good favorite of mine to sell when i started out. They can be bought of NPCs at Jita for 600k ISK and normally sold for 1.3m ISK in Dodixie.
However, at the moment there are 19 for sale at 997.9k ISK.
Unfortunately, volumes of sale per day are between 0 and 2, as shown below.
Hence, one sell order has c19 days of sales up which will only force a price war but, and here is the catch, without enticing more buyers into the market.
All the other sellers know that they can either wait 20 days (likely longer because further other sellers will be trying to get the lowest price) or they can discount in an attempt to be the cheapest when a buyer pops in.
People do not buy this Blueprint because it is cheap, they buy it because they want it now and are willing to pay 1.3m ISK if they have to.
They effect on the price is clear to see from the chart below:
The seller of the 19 items just got too greedy . . . . . or this seller may force the other competitors out of the market and so take the market for themselves. But they are likely to drive the profits down to 300k ISK per day - and if they allow prices to rise the old sellers will come back in. Taking the entire market in what is quite a small market is perhaps not the best use of time here.
. . . . . . and of course, volumes will remain at 0 to 2 per day, no matter how low the price goes!