I am not sure of your final purpose. You might have to use a join if you mean to literally plot observations of temperature and cost that share a common or nearly distance. If instead you simply want to explore and examine the relationship between temperature and cost via distance, what about modeling temperature by distance and modeling cost by distance, saving each model as a column formula, then copying these formulas to the same data table or a new one with a distance column. You could plot temperature and cost as Y against distance as X in Graph Builder now. (Graph Builder does a great job with formulas!) You could also plot temperature against cost directly. You might have to play with the number of rows and increments for distance to get the resolution you want in the plotted curve.