index=app sourcetype=application1 source=server1production with this search I get back two field Baseprice and finalprice. How can I build a chart that show the difference between finalprice and baseprice?
not cleat what you want, I am guessing you want some sort of final price (y axis) over baseprice(xaxis) and also the difference.
If so, try this |chart values( finalprice) by baseprice| eval diff=finalprice-baseprice
Use format option in visualization > select diff as chart overlay
But as @adonio says, are your fields numerical?