For those of you that have a 2004 ST4s and prefer a printed shop manual there is a limited quantity of inexpensive ones ($25 vs $$$$) on ebay at this link:
If you have a 2005 ST4s you also need this supplement, available for $15 at this link:
Shipping was included, so I spent a total of $40 for both manuals - not bad.
Note that both of these are the ABS versions of the manuals and that might be why they are cheaper, but they have everything the non-ABS versions have. My bike is non-ABS but I am well familiar with Brembo brake systems so no biggie. I do have a pdf non-ABS SM for the 2001 ST4 that should have pretty much the same brakes.
I had spent a lot of time on Google and forums trying to find downloadable pdf copies for my 2005 ST4s without success. None of the free download websites had it. Most of the for purchase pdfs were incorrectly described and I obtained paypal refunds on both that I purchased because they were for the earlier (2000) 916 based ST4. I don't know if they have yet updated their product descriptions based on my feedback or not but caveat emptor.
Part of the reason I burned so many hours looking for pdf manuals is that I was not aware that it was a 2 part manual: 2004 + 2005 supplement. This did not become apparent until I went to ebay.
Once I went to ebay I was able to find printed factory workshop manuals but most of them are $85+ except from this vendor who reports that Ducati no longer makes printed manuals. I don't know about you but I am happy with printed manuals and these are the nicest factory service manuals I've seen from any manufacturer; slick heavy paper, clear color photos, in Italian and English.
The only fly in the ointment is they are A4 sized paper with 4 hole punch and loose leaf binders for the manual and the supplement would cost more than I spent on the manuals, so I used zip ties, which allows them to lay nice and flat.