I worked at a PetSmart for a number of years and so have some experience with Wet Tail. We would get a shipment of Hamsters in at least once a month where they would come down with it. There are several medications out for it, and as far as I remember most the Hamsters we treated made full recoveries within a week or two. Last I checked most petsmarts carry the medicine for it (we just pull some meds off the store shelves every time we needed it)
Here is some links to a few of the products.
This is the one we most often used in the store.
This one might work just as well.
Good luck.