I have the typical three stall garage, with one stall being "mine". I have all my tools on wheels. 11 tools to be exact. Lately I have been modifying some of the wheel sets. I originally had everything on the htc systems as "zig" mentioned. I still have several tools on them.
They work fairly well if you are tolerant of a couple things. The tools all sit at a slight angle until you lower them onto the adjustable pads. They tear your work boots up on top where you "flip" the wheel contacts over and the wheels stick out 8 inches or so.
I have a set of wheels made by General, which also stick out a ways but they push straight down and are made for heavy duty tools. I have a 700 lb planer on them. They work well...pretty pricey.
As in your original post though, you want to avoid building your own. Actually, I am in the process of building my own for some of the tools and getting rid of the boughten ones. By building your own you can in most cases lessen the footprint, and get better wheels for less money. I have noticed recently that you can get double lock wheels for 8 to $15 in a miriad of places. One of the better places is Woodcraft and Highland Woodworking. I usually buy two double lock and two non-swiveling, no locking so I can steer it easier.
The other thing I have noticed is the manufacturer wheel set that are made for the machine are infinitely superior to whatever you are going to buy as an aftermarket. Lately I have been spending the extra cash and getting them when I can too.
Just my .02 worth...I wish I did not need any wheels, and I could just set everything up in a permanet spot like many of the shops shown here, but this is what I am stuck with for now, so I have been trying to refine the solutions.