They are very nice . They get about 3 ft tall with at least 100 flowers on them , they do tend to need to be staked up from all the weight and do require moist soil.
http://cubits.org/notfortheser...
here is a link to a co op that has 2 other Helenium in it but they are also asking for interest in plants so you could ask and they will see if enough people are interested in it.
I also want to say I am not sure if Mardi Gras comes true from seeds ,I think it is a hybrid which would result in flowers that are close but not quite the same.