Crested are great starter geckos.
Very easy to care for, 68-78 degrees is really ideal, if the temps are comfortable for you they will be for your gecko, they do not need for supplemental heat or light. Temps in the 80's will stress them and can lead to death.
As far as humidity goes misting twice a day is all it takes to provide proper humidity.
They can eat bugs however it is not a requirement, they do fine with only CGD (aka crested gecko diet, a powder that you mix with water), this means if you do not want to deal with bugs you do not have to. However if you do want to offer bugs crickets and dubias are a great choice (I prefer dubias since they have a better meat/shell ratio, are resilient and do not stink like crickets do). Cresties will grow faster if they eat CDG (fresh CGD provided every other day and Bugs provided at least once a week)
They do well in tanks as well as in tubs, a small critter keeper for an hatchling will work fine as a temporary solution until they are big enough to be housed in their permanent home so will a 10 gallon tank (need to be used vertically). Plants I recommend plastic so they can be cleaned. Substrate I prefer paper towel it is absorbent, holds humidity and can be easily changed when soiled.
Personally I am using tubs (much easier with multiple animals) and I found the perfect ones too that have a front opening cutting down on time when doing maintenance.
As far as housing goes 2 females can be housed together if they are the same size however when young they may compete for food, which means one can get bullied and not grow as fast as the other which is why I recommend to house animals when full grown or close to full grown.
Males should not be housed together.
You can have a male and female together however I recommend to separate them to give the female a break, and of course they should only be housed together when both optimal weight for breeding.
Here are some good sources http://www.acreptiles.com/main/index...=53&Itemid=316 , http://www.pangeareptile.com/store/c...-sheet-en.html
As far as pricing it can go from $50 to $1000, it depends on the mutation and quality of the animal, there are some very high end cresties out there..