I would recommend that you contact your local Snap On rep. They are listed in your local phone book or you can swing by the local Ducati shop and ask them who their Snap on rep is. Now granted they are a little on the expensive side but they truly are the best tools that money can buy. Isn't your Duc worth it? I was able to get a 10, 12, 14 and 16MM allen socket for under $50.00. You may be able to order direct from Snap On on their website.
find a real tool store or order online from Sears..Quality tools last. I still use the snap on screw drivers I bought 20 years ago and they will be handed down to my son.
BTW, the $$ you spend once on the proper tools to change your oil once will be recovered w/ the money you save on doing your own..
Lastly, these are common motorcycle size tools. In a previous lifetime, I was a factory mechanic for Yamaha and Suzuki and believe me, these are common tools, wait till you need some special tools (anyone need a valve shim holder for yamaha 4 cyl. inline circa 1982-86??)
If you start on the Sears homepage and select Tools, then Mechanics Tools, you will get a list. Select Three Quarter or Three Eighths or One Quarter Inch Drives and Sockets and it will bring up a page with a bunch of fields to select to narrow the search. Metric sockets is one of the options.
I got the 10mm allen (socket type) at my local auto store. It was fairly cheap - 5-10$. Works fine. You could also go the cheaper route and just buy a 10mm allen - cut it and fit the end in a socket - or just use the allen as is.
The drain plug is the same size as the old- I mean really old- VWs. I had an allen wrench in my tool box from back in the 70s that fit. Maybe just check out your local Checker/ Auto Zone/ whatever stores.
So far , the only 14mm item I've found on my 95 M900 is the front axle. While playing around with different quality nuts and bolts at the hardware store, I found that 9/16 SS nuts would fit in a 14mm socket where others wouldn't.
So for an axle tool, I put three nuts on a bolt and welded them together. Then dressed each surface flat and smooth with a file until it fit. It makes a good little slug to stick in the axle and put a socket on it to turn the axle.
All the other sockets and stuff I've been able to find at Sears.
The local AutoZone in Denver, CO had a three pack of allen hex sockets (12mm, 14mm, 16mm) for something under $10, as I just recently ran into the same problem of trying to find an allen wrench or socket to remove the oil screen (turns out it's a 14mm). Snap On was also suggested by the Duc dealer, but I of course had the oil drained and the bike sitting, so visited about 8 different auto, hardware, and tool stores before finally finding what I needed at AutoZone.