LOL mike.. Do you want to sell me ONE of those dryers?
I actually use each one of them for specific things.
We take the Double K or the K9-II to shows, depends on what the show site will be like as far as available electricity. Usually can only run one motor on the K9-II at small shows, so using the Double K works just as well.
My shop vac really gets used mainly as a vac, since it doesn't put out the airflow volume of the dryers, but I have found you can vaccuum the dogs with it from time to time and get some loose hair off....and it helps keep the area tidy from all the loose hair that accumulates from using dryers.
The K9-III (recent acquisition) is reserved for heavy duty use (post water training bath or pre-show bath) where we need some serious drying action. Keep in mind both our boys have pretty thick coats, and even the K9-II with both motors isn't fast enough to suit me, which is why I added the beast of dryers.
You can certainly make do with the shop vac for a bit, and it is worlds better than traditional hand dryers, but long term, you'll still want to consider a dedicated dryer. There is another one, which I don't own but have used, made by Laube that is sort of a middle of the road dryer that isn't super pricey and you could potentially consider as well. Save you pennies, and get what you are most comfortable with.... but trust me, once you do take the plunge, so to speak, you'll be using the blower vac the same way I do.
-Mike