I received my new telescope cover the other day, it is a "Telegizmo" brand cover, I bought from Highpoint Scientific in the US for around USD$50. The model I got was the TG2D which is supposed to be for 10" and 12" dobs (but I suspect you could get both a 10" AND a 12" dob under there together ). It seems very well made from some kind of "Space Age" material - "multi-layer, polyethylene material with a fully aluminized surface" - developed by NASA, it's red inside). Has a draw string at the bottom and as you can see covers the entire scope including the rocker box and has enough room to park it vertical or down to at least 60 degree angle. Looks like it will do the job quite nicely!
I have one for my C9.25 and one for the Tak EM200 and they are very well designed, constructed and I now use them all the time when I leave the gear set up in the back garden. I can thoroughly recommend them.
I purchased mine from Jim at Scopestuff. Here is the link:
Much harder to blow a dob over since the center of gravity is so low etc.. then again, if it's blowing that much you're probably not going to take your scope outside anyway..the covers are not designed for permanent outdoor storage.
Looks nice..
I bought a motorbike cover from supercheap auto or autobarn, can't remember which. Cost $40 but fits over the dob on the trolley, and is waterproof.