The Unitard
Her Coat Is Of The Tabby Kind, With Tiger Stripes And Leopard Spots
UNITARD - First thing once you have decided which Jellicle you are going to be is make sure you know which type of unitard that Jellicle uses! Some Jellicles have mock turtle necks on their untards, and others have scoop necks. Just in case you don't know which is which, Tantomile and Coricopat have a scoop neck, while Etcetera and Alonzo have mock turtle necks. All of the Jellicles wear unitards that have a full back with a zip up back or side. Like the wigs, both styles can be purchased at ADA Discount Danceware. Or, if you are one of the sewing inclined, you can opt to make your own (this makes it a little cheeper, but it takes more time and can be difficult if you haven't worked with elastic material before). Unitards are typically made from either nylon/cotton or lycra/cotton. The nylon will be warmer, but it isn't shiny like the lycra is. I've also been told that nylon tends to accentuate body flaws. 
Fabric markers are good for cross hatching smaller areas on the unitard (take a look at Bombalurina, Demeter or Rumpleteazer). If you're doing costumes with large areas of one color, such as Mr. Mistoffelees, airbrushing is good. Floral dyes also work well. For shoulder fur, there are two real options. First, you could sew on fake fur, which can be purchased at any fabric store, and a lot of craft stores. Another method is to use yarn. That is a longer process where pieces of yarn are strung through unitard, and are tied off at the bottom. Then the two ends are fluffed with a dog grooming brush or a toothbrush.
Okay, first of all, I am one of the above mentioned "sewing inclined," and probably also a little masochistic. I love to sew and find that it usually makes my projects a little cheeper (only a couple of bucks, but you don't have to pay extra for shipping!). However, if you plan on a lycra bodysuit and don't have any experiance sewing with it, get someone to help you. The nature of the material makes it somewhat difficult to work with if you haven't done it before, since it is slippery and will slide while sewing and cutting if you're not careful. The lycra can ususally be purchased at any fabric store in the two colors usually associated with CATS costumes (black and white). Since my costume will be Mistoffelees, I'm using black material. Those people who are going by the video will note that Misto looks like he has a white unitard that has just been cross-hatched to death. This is probably the truth. I am honestly just too lazy to do that, and I'm also considering that faberic markers run about $3 a pop. Most of the other Jellicles require white as a base color. 
The material is a little on the pricy side, usually running about $7 or so a yard, depending on the season (more expensive in spring and summer when people are making swimsuits out of it). But it is still cheeper than buying one if you don't mind a little work. The pattern I reccomend is the Kwik*Sew #2108, view B. Hancock Fabric stores usually carry this brand of patterns. The pattern runs about $8, but it really isn't a bad deal considering pattern prices as a whole, and considering that this is a master pattern that you can use for multiple costumes. You will also need one 22 in. zipper. I reccomend the hidden kind, which are harder to see. When sewing, if you do not have a surge-overlock machine, use a zig-zag stich. 
It will give you the same strech as a surge machine would.
The shoulder fluffies (in Misto's case, chest fuzzies), I made from yarn. Just knot it in the pattern you want, or you can glue it if you use small enough patches of glue and space them far apart. Some people use fake fur, but I think the yarn looks nicer. But let me warn you, it will take a while to do. It's enough to drive a cat loopy! Might I reccomend Mello Yello for those late nights of sewing? >^_^<
Fabric markers are good for cross hatching smaller areas on the unitard (take a look at Bombalurina, Demeter or Rumpleteazer). If you're doing costumes with large areas of one color, such as Mr. Mistoffelees, airbrushing is good. Floral dyes also work well. For shoulder fur, there are two real options. First, you could sew on fake fur, which can be purchased at any fabric store, and a lot of craft stores. Another method is to use yarn. That is a longer process where pieces of yarn are strung through unitard, and are tied off at the bottom. Then the two ends are fluffed with a dog grooming brush or a toothbrush.
The material is a little on the pricy side, usually running about $7 or so a yard, depending on the season (more expensive in spring and summer when people are making swimsuits out of it). But it is still cheeper than buying one if you don't mind a little work. The pattern I reccomend is the Kwik*Sew #2108, view B. Hancock Fabric stores usually carry this brand of patterns. The pattern runs about $8, but it really isn't a bad deal considering pattern prices as a whole, and considering that this is a master pattern that you can use for multiple costumes. You will also need one 22 in. zipper. I reccomend the hidden kind, which are harder to see. When sewing, if you do not have a surge-overlock machine, use a zig-zag stich. 
It will give you the same strech as a surge machine would.