You can always make you own, have a look at some of the threads on this forum, regarding
workshops,
workshop designs, lay outs. have a look at mine at
http://picasaweb.google.com/snichols33/Workshop# mind you that was at the end of 2008, looks a lot different now, not as tidy.
I made my mountboard storage out of 3/4 ply with 4 fixed casters on the bottom ( now I would put two steering casters on, as they never run straight at the moment). The benches are made out of 4x4 for the legs, 4x1 for the cross bracing and 8ft x 4ft 19mm chipboard for the tops, shouldn't take too long to knock up, did mine work benches in a day.
Once you have your workshop built, design you lay out on the floor, using chalk to mark out where you are going to put everything, then you can have a walk around (even carrying a sheet of invisible glass

) to see if the layout works and if you have enough space to move, then build the units.
Wishing you luck and keep us posted
Steve