@Hugh and Annihi:
The process for gathering any material in this game seems to include at least two processes (three for noralgis)... mine or harvest, then transport it. With noralgis there is a host of other problems, so setting that aside.
Given the similarities, lets just compare triandlus and helioptris. Given the volume disparity, it seems that a gathering-focused character would never in his right mind gather heliop for sale to the market -- because of the logistical problems.
Translating this into multi-role characters (or multi-account obsessed fanatics like myself ;-) ) it produces a dynamic wherein it never makes sense to sell helioptris on the market; I need it for my stuff and my Corp's stuff. Because I am certain I am not the only gathering/miner who has made this calculation, there is seldom much helio on the market at the scale needed for producing say... Lithus robots.
Demand-side is one factor of the pricing equation, the other is supply-side (what I feel it would be fair to sell at given my time/work/effort in gathering the material....). I would argue that given its volume it makes no sense to sell it at any of the price ranges I've seen. Adjusting its volume to make it comparable to triandlus would help enourmously IMO.
My $0.02. :-)