Ah Chinchillas...wonderful pets that don't get enough attention.  Before you decide on one though there are a few things to keep in mind.  Mainly, a chinchilla needs your DAILY attention (although leaving him/her alone for a weekend may work...but more on that in a minute).

Here's your basic supplies needed:

1)  Suitable caging - This is a big one as far as I am concerned.  Most people tend to buy those wire floored cages which are great for you for cleaning, not so nice on those little feet.  Please people, buy a cage with a solid bottom or build your own.  BUT, if you do build your own please do a websearch as there are woods that are a no-no to build out of.  The most common is untreated kiln dried pine (usually marked with KD).  Also, melamine is used but please no exposed edges.  UPDATED:  No plastic please - what was I thinking LOL

2) Water bottle - A small glass one looks nice, but it is easily broken when your chin pushes it and it's also, well small.  Go for a bigger plastic one and make sure to fill it with fresh, filtered water daily (or at least every few days - this is where the going away for a weekend comes in).

3)  Hay - chinchillas love Timothy hay, both loose and in cubes.  My particular chins also love it as a cage bottom (vs pine shavings).  Give them plenty every day.

4) Pellets - ONLY USE ONES MADE FOR CHINCHILLAS.  Chinchillas are not rabbits, nor are they guinea pigs, nor hamsters so don't feed them as if they were.  Mazuri is a great brand to use.

5) Treats - my chins LOVE treats.  Their favourites are shreddies, raisans, craisans, and banana chips.  Careful with the amount though, just one a day max for the shreddies and one a week max for the rest.

6) Wooden Toys - Chinchillas are a member of the rodent family and so they like the chew.  Please give them something to chew on!  They LOVE apple, willow, and untreated kiln dried pine.

7)  Somewhere to Sleep - Chins like to sleep hidden out of the way from the sun.  There are a few options including wooden huts, flower pots, and pails.  My chins love their hut so I would tend to recommend that.

8)  Dust Baths - Chins need to take a bath - a dust bath that is.  No water for these little guys and gals.  There are specially made dust baths you can buy, but I tend to use a medium-sized glass bowl and put about a tablespoon or two of special dust (sold in pet stores).  I place the bowl in the cage and let them clean away.  The best best dust if you can find it is called Blue Sparkle or Blue Cloud.  They are pretty much the same but the sparkle...sparkles.

9)  Attention - Chins love attention and they love to be talked to and petted.  Chins also love to come outside their cage (careful they are fast) and run about.  Most people I know put them in the bathroom to run about and others let them run about on their couch.  I tend use a combo of these.  UPDATE:  Please do NOT use a plastic wheel ball no matter what it says.  Chinchillas will overheat.

So that's a chinchilla in a nutshell.  Before you get one do your research please.  They are easy to care for and very soft and loveable...but they also live for about 20 years.