Some example with details about the kind of campaign you ran.
What was the total cost or daily cost of that campaign.
How much traffic turned up.
How many sales / conversion happened in case if u tracked that.
What was the time required to setup this campaign.
If I ask you I need this much targeted traffic which has high rate of conversion can you give me a quote of a PPC campaign based on which I can decide to invest on you.
Please share more spreadsheets or details of your previous campaign runs to give us a better idea of your expertise.