Gary, 'Shockwave' (patented) was introduced in 2010, so it makes sense that it might be more available.
On the other hand, I've seen 'Nora Leigh' (been around longer, perhaps a lot longer), more often for sale here.
Perhaps it's because it's not patented.
Actually not sure about the spelling of the name 'Nora Leigh': is it 'Norah Leigh' (name I used to use)? Probably should have stuck with the Royal Horticultural Society spelling and have ignored Dave's Garden.
Things thinning out here:
This is Aconitum (Monkshood) 'Spark's Variety'; grows about 7 foot tall in our garden.
This old phlox grows about five foot tall.
It could be 'Robert Poore', but got it, unnamed, from a local horticultural society sale.
(I actually purchased a named 'Robert Poore', which the plant I received definitely is not).
Doesn't seem to take a good picture ('Orange Perfection'), but it is one of the very last garden phlox to bloom here.
Added the Echinacea (Double Scoop Orangeberry) several months ago and they still look OK.
Recent repair work; smooth asters and Echinacea.