The issue with any bike when trying to scope the maintenance costs is simply how much you intend to ride it. E.g., if you do 12000mi/yr, then you know *part* of your answer.
Case in point, I commute 40mi/day, in all weather, roughly 220 times a year (other times I work from home or take a car).
That would be 8800mi/yr on the face of it, plus the occasional (and I do mean occasional -- 2 kids) rides for fun which, if I'm lucky, total 2000mi. So, 10,800mi. With your maintenance cycle, that's almost two full services in the dealership. There are a couple of other issues to consider along those lines, however.
Your ST, much like my Hayabusa, will easily need at least one tire change in that period, and probably two. That's cost of tires -- probably ~$250-300 -- plus mounting, which can vary but bank on an hour's labor, so the total can safely be north of $350.
Lastly, the number one headache isn't even the raw cost. Your dealership is busy, no matter who they are, so you'll have to make an appointment with them or leave the bike for a period so they can fit it in (say, a week or so). In summer, that appointment may be weeks off. So, when you have tight maintenance intervals the primary issue isn't even the money, it's timing. You have to watch your miles and know exactly when you're going to need tires, oil, and engine work and line up the shop time, or find it's not safe to ride while you wait.
Everybody has to do oil changes, but in my case (unless I want to do the filter) I don't even have to take off the plastic to do that and it's commonly a 15min task I can do anywhere. That's a lot of time I don't have to spend ferrying the bike and waiting for shop time. Blissfully, my Hayabusa now runs Metzler Z6 tires, which wear about 8000mi (what I used to use was done in less than 3000, but that's a common problem with big sportbikes), and my valve intervals are, practically speaking, 20,000mi.
So, since I do my own oil, my only mandatory shop time is somewhere around every 8,000mi, as opposed to oil, valves, *and* tires spread across the year at different points.
You have no idea how much of an improvement that was over my old BMW or KTM, both of which had 6,000mi major services and were a hassle to change the oil for, so I spent lots of time heading back and forth to the dealer. This is a serious issue if your dealer is at any distance, BTW. I have a Ural, in contrast, that wants valve adjustments and oil every 1,500mi, but OTOH its a 2-valve, mechanically adjusted airhead and I can reach them with a single bolt and adjust them out in the open in about 15min. It still has three fluids, however -- engine, tranny, and final drive, but that's also easy to reach.
So, the maintenance picture is actually pretty involved. Ducatis are vastly improved in terms of their historical, Italian-esqe reputation, but those intervals, particularly in a heavily-faired bike, are a significant time sink in practice.
