In general, you don't need the part to have a mold made. You do need a drawing of the part.
Get a copy of a good 3D modeling program (I use the free Alibre Express) and make a model of the part (or of the mold). Use it to produce dimensioned drawings. Take it to a mold maker and get a quote.
Then determine that it is way out of your price range and try another approach. :-)
[I'm somewhat over general here. For some parts, having a sample is all you need. For example, if a wanted a mold of my face, I could use plaster to create a mold without having a drawing.]
Can you give us more info? What will this part be made of? How big is it? How many do you need?