If you want to buy the "Ford Authorized" shop manual quickly, Helminc is the place:
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http://www.helminc.com/helm/homepage.asp?r=http://www.google.com/search?hl=en&q=Helminc&btnG=Search
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Remember that a Windstar is a Ford "truck". Also remember that electrical diagrams are published/sold separately from the shop manual ... so look for it to be listed separately. Helminc is the place for fast service.
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If you want to save a few bucks ... and can wait a few days (if the books are not "now on shelf"); You might try the following folks:
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http://www.books4cars.com/
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I have used Books4cars for Mazda factory shop manuals ... have recieved the electricals, am waiting for mechanicals ... but will pay no additional shipping for delayed shipment, and of course, I have only been charged for manual that has been received. Books4cars also sells the Haynes and Chiltons ... so be sure to specify factory manuals if that's what you want.

12Ounce
I got my factory manual on ebay $9.95 plus $5.00 shipping. I also got the vacume and wiring book for $7.00 . They looked like they were from a delaer that went out of buisness but in great shape.

That was a very good purchase!

Ebay is always worth a try ... but I've never found exactly the manual I needed ... when I needed it. The CD's are always available, but I'm old-school and like paper.

12Ounce
I too have used the cds but they are a pain to find things on, the manual is so much easier and much more complete. I also have an Alldata subscition for the windstar and a blazer. It is well worth the money.

That was a very good purchase!

Ebay is always worth a try ... but I've never found exactly the manual I needed ... when I needed it.
Having purchased about half a dozen factory manuals over the past few years on eBay, I find it's "being in the right place at the right time" to get the manual you need at a good price. The longest I've waited for a manual for my year and in the price range I was willing to pay was about 4 months,( not good if you are in an immediate need for one,) but like I said earlier good things come to those who wait. I think the most I paid for a factory manual was around $22. It pays to be patient sometimes on eBay also. I've seen sellers who did not sell their manuals the first time, relist the manual for a lower price, and I've also seen 2 or 3 manuals for the same model/year for sale at the same time and then it was just a case of deciding which was the better buy based on condition and shipping charges.

I have found that another good place to pick up a shop manual is my local library. Ours has about every publisher's version for about any vehicle imaginable.