I think the current price of the Heavy Lance is due to the first balance attempt when it was the undisputed king of lances, unsurprisingly balance by upkeep proved ineffective. So they now balanced it by stats, a little heavily. Currently there is indeed no reason that the Heavy Lance should be in a different price range as the other lances.
Light Lance is my favourite lance as an armour, heavy horse and strength crutching lancer. I have no qualms taking on any other lancers head on, as few seem to be really proficient at using their lance to its full extent, especially when I do tactical slowdowns. When fighting infantry the Light Lance is just amazing and when dehorsed it is relatively bad compared to awlpikes and the lot, but still very usable.
Heavy Lance deserves at least a price decrease to 6k and probably a 1 or maybe 2 damage increase. Although I don't know to what extent the slow speed rating attributes to the damage after speed bonus. Maybe with a +3 courser and high riding skill doing full speed hit and runs is actually very effective? I can't be arsed to try it as that is the complete opposite of my playstyle as cav, but if anybody can comment on that?
190 reach overheads make for great support, think about it. Not shabby as a hoplite weapon either.
You are wrong. It's horrible by any standard. Sure you can kill someone with it, but you can also do that with a sickle.