miners have very little effect on the market
Miners don't have effect, the supply does. And supply will reduce twice.
(Miners costs don't have effect because of difficulty)
Reduced supply should drive price up (if there is a demand).
i would say only ~5% of the daily volume is miners selling their coins.
maybe when the reward is cut in half price will get pumped... but i know theirs a lot of people (including miners) holding their coins until that time.
they will wait for the new highs, from speculation on the effect of the reward being cut in half. and then start selling their coins they have been holding for a long time!
so once the reward is cut in half maybe ~20% of the daily volume will be atributed to minners selling coins!
i expect a pump and dump for the 25BTC reward phenomenon.