50shep: For what it is worth, that listing is from Johnny Law Motors and I have had good experiences with them in the past.
Based on your username, I am guessing this is for a 50?
LMC has an electric conversion motor:
Wiper MotorsThey also have the linkage and related parts:
Wiper PartsJust between the 12V motor and linkage you are looking at $300, plus all the fiddly bits. In pure $$$, the ebay kit is probably going to be cheaper. It will take some extra effort because you have to get it set up and installed for your specific application.
Being able to just follow the FAM and get spare parts down the road if something breaks or wears out might be worth the extra cost. It also might be worth calling Johnny Law and seeing if they sell spare parts.
I would caution you against putting dummy arms on. The cops have little to no sense of humor and if you do accidently end up out in the rain you will regret not having functional wipers.