Drop Down Menu populating Cost box issue

Hey guys first let me say thank you for all the help and guidance you have already given to the lug heads out there like myself. Here is my issue, I am trying to put together a functional invoice. On sheet 1 (called Invoice 1) I have my invoice template. Boxes A17:A39 are drop down menus of services and products. One Sheet 2 (Prices) I have put two lists (they are identical, I just made one a table during this experiment) with the Items listed in boxes C3:25 and prices listed in D3:D25. What I would like to be able to do is when I pick a product/service on the Invoice (Sheet 1) on the drop-down menu (A17:39) then it automatically populates the cost category (C17:39). I have attached a copy of the invoice if anyone would like to see what it is that I am trying to do.
Thank you in advance for any assistance or help anyone can be. I know it's not a difficult formula but even after all the stuff I have looked up on this website and others I just can't see to wrap my head around it. Thanks again.

Thanks for your help man. That helped a lot, but did bring up one thing I need to add now. I would like to add a "N/A" to the drop down menu (in case I don't use all the spaces on the invoice) and would like for a "0" to appear then on the cost. I have added both the "N/A" and "0" to the item/price list. So now the product list goes from C3:26 and price list D3:26. Right now this is what I get "#N/A" in the price box. Thank you again for the quick help.