1. encolsure size...
a hatchling can be house in a shoe box sized container with a secure lid. A 20 gallon long tank (or 29 high) would be big enough for one corn throughout its entire life. the general rule is that the length plus width of the container is greater than or equal to the length of the snake. It is not recommended to house two hatchling or other younger corns together because of a risk of cannibalism and stress. Housing adults together is less risky but should only be done with two females as 2 males will fight and a pair will breed which can be dangerous if the female is not big enough. I only house one pair of corns together but both are breeding size/age. they are housed in a container that is 38"x~20". and it is 7 inches high. height is not required but with short tanks have a very secure lid
2.temps
my corns enjoy a room temperature cool side(70-74) and a heated(with a UTH) warm side with the temps(76-80)temps can vary just not drastically and the gradient is important so a snake can thermo regulate.
3.Humidity
I don't do anything special except have a water dish in their enclosure that is large enough for them to soak in. this should be enough but some corns have trouble shedding so you may have to raise the humidity.
4.biting
Corns don't bite very often because they tend to be more docile animals. Younger conrs may bite because they are scared but with regular handling they should calm down. i got bitten once by one of my hatchlings when i first picked him up after bringing him home, it doesn't hurt. But every now and then i get bitten by my yeralings because they are starting to get bold and i have mouse smell on my hands. it still does not hurt to me but my largest yearling drew blood the last time she bit me(she is 35 inches long) My older corns have never bitten and have the sweetest temperments. so i have no idea what it would feel like if one of my big ones bit me 
5. price
price depends on many things. where would you buy them? what colors do you want? what age?
as for the stuff... i paid 9.99 for a bad(5cubic feet) of substrate(i use aspen) i make my hides out of boxes or pvc piping so they are free to cheap. if you want to buy expect to pay $7 for a nice hide(up to $15 even) you will also need a water dish which can be simple or otherwise($2-15)As for the cage it depends on what size you are getting and if you are going to get two corns you will need 2 enclosures, so it depends...
6.cage requirements
minimum requirements are a hide on the warm side and a hide on the cool side and a water dish on the cool side. Substrate can be many things like aspen, papaer towels, carefresh, etc... but NO pine, cedar, or sand. you will also need more hides if you have a young snake and you may want to decorate a little more but this is just minimum. also you need an under tank heater(UTH) to make the warm side warmer than room temp.
** also i suggest you do some more research and ask more q's on this forum. I also recommend The Corn Snake Manual by Bill and Kathy Love, it is a must for any corn owner and should be read cover to cover twice before you get a corn.
also check out the caresheet on this site as well as at the link below. the link is to South Mountain Reptiles, there they have a really good care sheet and you can see their pricelist and pics of a lot of the morphs out there. Good Luck! 

South Mountain Reptiles
-----
~~~Amy~~~