I am not 100% sure what your question is asking, but I think you are referring to selling an item to make profit.
If you are talking about $USD, for example, you could say:
- "The mark up on that TV is $100, they only bought it for $200."
But normally we speak about a "mark-up" as a percentage - for example:
- "The mark up on that TV is 50%."
I hope that this helps, Tom