Welcome to the forum! you must be pretty excited about your new pet! I'm pretty new here myself but everybody is so nice and full of helpful information!
The FAQ sticky is a good place to start for basic info:
http://www.cornsnakes.com/forums/showthread.php?t=28341
I'm sure the experts will have more specific information but I figured I would just let you know what I've experienced so far. Please keep in mind though, the prices I'm quoting are from memory so may not be completely accurate!
The prices for everything will depend on where you buy them. If you go to a petstore like Petco or Petsmart, they can run a little high but I didn't know this when I first got my snake...
At Petco, I bought a 10-20gal Heating Pad for about $23,
Aspen, I think at Petco was about $8 for a small bag (10-20gal) but I was at walmart last night and found a good sized bag of Aspen for only $5. You should have seen me dancing in the aisle when I found it!!
As for hides, store bought ones are easy to find but can get expensive. You can use things around the house like toilet paper roles (if you do a search on this site for toilet paper tubes, you'll find some really cute pictures of corns peaking out of their tubes!), upside down clean butter tubs with a hole cut out, etc. I bought some silk plants from walmart for $3 and just used suction cups to attach them to the sides of the tank.
Walmart has digital probe thermometers for $7. I use the digital probe one on the warm side of the tank and then on the cool side, I use a stick on thermometer right above the bedding line that I got at Petco as part of a package with a humidity gauge for about $6. However it is my duty as a cornsnake.com user to advise you that regular stick-on thermometers are not always completely accurate and not the best to rely on.
Petco has packages of frozen pinkies for $4 for a pack of 3 but I've heard you can buy in bulk online for overall cheaper prices.
It's always a good idea to look around and see what you already have at home and visit multiple stores and/or websites to compare prices.
My snake has never bit me so I can't answer from firsthand experience but I've heard on here that it does not hurt at all. Maybe the equivalent of a pinprick but don't worry about this and especially don't let your snake sense your nervousness.
I hope this info helps a little bit! Again, welcome to the forum!!