I see that you are referring to Condition type - Cost. Is it VPRS condition? Also, I see that there is a formula 900 used to calculate condition base value.
If VPRS, I think thats connected to the Cost of Goods Sold, posted while doing PGI for the outbound delivery.
If not, please check if you have a program named RV63A900 in your system. Please try to put a break-point in that program, open VF03 again, and navigate to Conditions screen. The program should break at that break-point, if the formula is getting called. The calculation for pricing will be in that program and you should be able to read through that program to understand the same.
If both these steps didn't work, on the Conditions screen, there is a button named "Analysis". Once you click on that, you will see a list of condition types from the pricing procedure. Please locate the condition type you are concerned about and open the nodes below that condition type. Each of the steps under the condition type, should give you some information on how the calculation is done.
If you are unable to follow, please reply with details on the steps you did, with screenshots, so that we may further assist you.
Thanks,
Juwin