I think that prices will drop and level off. I do not see prices for more-prevelant morphs sugh-as Pastels and Mojaves sinking to the normal-price, though. Normals are mass-produced and captively hatched/farmed; morphs are not. Even if you spend $600 on a Pastel this year and bred it in 3 years when it matured or so, I do no see you losing money in the long run if you had healthy babies hatch out.
Every day, more people get into this hobby and want lower-priced morphs to start out with. I do not see a vanishing demand for Pastels, spiders, etc.