After looking at all the local nurseries within a hundred mile radius and ebay and still not finding what I want I've finally located sellers of hard plastic 2.5" and 4" square pots (not the flimsy jiffy pots) and 21" x 11" sturdy, form fitting (holding each pot), draining, space maximizing carrying trays to fit them. Right here:
These are the ones they use at the nurseries that I like when see them but aren't available for sale to the public.
They do have other size and shape pots and carry trays too if you like bigger or other styles. No rediculous minimum quantities and free UPS ground shipping on orders over $75. I'm not advertising for these people (per se) just letting you know where to get these space saving pots and trays incase you've also been fruitlessly trying to find them like I have... until now!
And tomorrow's my payday... "O O Hoppy Potty"!