Substrates and Other Cage Materials
There are many types of bedding and substrates used for snakes. I have not used them all, but will cover the ones I have used.

Newspaper  is used by many herpers. The Barkers use it for almost all of their snakes. I used to use it, but don't anymore. Nothing wrong with it, just don't use it. I don't like the way it gets wet whenever a snake urinates or defecates on it, or when the water is sloshed on it. I've had many cases of blistering in snakes, particularly colubrids, from damp paper.

I use wood shavings for most of my snakes. I'm fortunate in that the local farm and ranch supply stocks excellent quality dry, clean pine shavings. I get them in packed 3 cu. ft. bundles for about $5.75 per bundle. There is little dust in them. They are the same shavings that I use for my rodents. There are advantages to the pine shavings. Cheap is one of them. Also, many of the snakes like to burrow in them, particularly the Dumeril's boas. They soak up moisture. Old shavings can also be used as mulch.

Do not  use cedar shavings. They can be toxic to many animals.

Cypress mulch   is also good for many animals. It can be dampened without much trouble. My rainbow boas, ringed pythons, Savu pythons and Sanzinia are kept on cypress mulch. The rainbows like to burrow in it, particularly since I have recently found more finely mulched cypress. Much of the time it has large chunks in it, but sometimes it can be found in a finer mulch.
Cypress mulch also makes a not unattractive substrate in display cages. at $2.75 for 2 cu. ft. and $3.75 for 3 cu. ft., it is certainly cheap enough to change when necessary.

Outdoor carpet  can be used also. It looks fairly good in some display situations. However, there are drawbacks.
It is hard to clean. I used to take mine outside and hose it down. Before that, I tried putting them into the clothes washer, but they tended to fall apart rapidly that way. Whatever method you use to wash them, eventually they will begin to fall apart.
Also, moisture will pass through the carpet, so you need to put a few layers of newspaper underneath to soak up the moisture.
If you are going to use outdoor carpet, buy the good quality. If you buy the cheap stuff, it won't last long.

Aspen bedding  is used by many keepers, particularly for colubrids. I don't use it for a few reasons. First, it isn't readily available in many areas, including mine. Also, it costs about 3-4 times as much as the pine shavings. Also it is small enough to be ingested and large enough to cause impaction.
Since others use it with no problems, I would say go for it if you want to. Not for me, but works well for others.

I use sand  for my Egyptian sand boas. I use washed play box sand, available in sacks from almost any home depot type store. Stay away from the sand used in mixing concrete. The sand can be sifted periodically to get out dried fecal pellets.
Some people worry about the sand being swallowed, but I have never seen any ill effects from this. It is fine enough to pass through the digestive tract.
I have looked at CalciSand, but have not tried it. It is expensive and I don't consider it necessary. A $2.75 bag of playground sand will be enough for 3-4 twenty gallon aquaria. The same amount of CaciSand would cost me well over $50. Also, regular sand doesn't dissolve with moisture. Stay way from large-grained sand and you should have no problems.

When using branches for cages, remember that may types of insects may be bored into the branches. Many times I have found wonderful dead trees or limbs, cut them to fit the cages, put them in, and then watched the insects proliferate. I used to have access to a huge walk-in oven so that I could heat treat the branches, but no more. Smaller pieces can be put in an oven and baked for a while to kill the insects hiding in them. Submerging them in water and then hanging them off the ground for drying should also work.
Try to use branches from a low-sap type of tree. Smooth bark is also a bit better, as it is easier to clean and less likely to be a hiding place for mites.