New here. Straight to the point:

 

As a f2p player in the oldschool game, the market community can be very small. As there is no grand exchange, it is incredibly hard to have transactions.

 

As I am currently stuck mining a hell lot of coal without much stuff to run this test,

 

does anyone know what the cost equation is like for stores?

i.e General store.

 

What I am referring to, would be, if I sell something, what is the chance of price decreasing, or the percentage decrease. 

 

perhaps we can get an collective information post so that this cost equation is figured out.

==

There's one done by someone, not sure if it still holds true, or whether it is complete 

 

 

I've been doing some research and i've found some things about about how the sell price of the shop goes down. My research covered SELLING items to them only. I found that

1. The cost decreases at the same rate until about 22 items, where the price drops slower till 23, where it stays the same.
2. The rate it drops by is roughly 1/27.5 of the price of 0 in stock.
   1. The rate it drops at 22 is half of that rate
3. The sell price of items is rounded down to 2 decimal places for figuring out the next one.
4. The sell price of items is rounded down to 0 decimal places for the actual price

I'll figure out a formula later but i also need to check another important point, which is that the Fishing colony general store apparently has higher prices than others.

-(http://runescape.wikia.com/wiki/Talk:General_store)

You're going to get shafted selling coal to the general store anyway, as the alch price is really low for ores :wacko: .  And yes, stores specializing in one area may give slightly higher prices for that kind of item.