Two of the departments that get screwed over the most in indie film-land are wardrobe and costume design. But it doesn't have to be that way!

Yes, I said two departments.  Costume design deals with the creative elements - matching clothes to characters, doing research, and working with the cast, director and the production designer.  Wardrobe creates, cleans, organizes and repairs the costumes, and keeps track of continuity.  This is similar to the way the art departments function - the production designer is the architect, while the propmaster is more hands-on.  In New York, union costume designers and assistants are in the production designers local (829); wardrobe staff are in another (864). 

But costume and wardrobe help each other out, and input goes back and forth.  On independent shoots, these two departments are often crunched into one person.

Many first-time filmmakers don't realize how big the job is.  Clothing is an indicator of character and ultimately of the deeper themes in your film.  Add in fitting, buying/borrowing/returning clothes, making alterations, dressing actors, and keeping continuity.  So budget wisely:

CREW

Do you at least have enough money in the budget for a costume designer and an assistant?  Usually the designer will have a favorite assistant.  If it's a one-person department, try to find an intern who's interested and won't get in the way.

WARDROBE RENTALS/PURCHASES

Start with your script.  Figure out the number of wardrobe changes each character goes through (typically one per script day).  Add these together and you'll get a sense of the total clothing "sets" in the film.  Add multiples of outfits if you have stunts or blood effects (you'll want backups of your character's clothes so you can repeat takes).  Uniforms, period costumes, and special items (headgear, armor, special jewelry) will cost more.  This will give you some idea of how much to budget for wardrobe purchases/rentals.  Some rewriting, thought and discussion with your designer can save you a lot of money - perhaps your main character only has one good suit or dress instead of five.

Your designer will need a credit card with a relatively high limit, so he can do buy-and-returns.  She'll also need your cast members' contact information, so she can reach out to them and borrow their wardrobe.  And prep time, whether paid (preferably) or not.  Your designer will need roughly two days of prep for every day of shooting; more if you have a period/sci-fi project.

GEAR

You'll need to rent racks to hang clothes on, bags, hangers, a steamer, and privacy screens so the actors can change.

On a shoot that's big enough to support trucks ($200K+), I put the camera, sound, and wardrobe departments in one cube.  Wardrobe racks are tied to one side, camera and sound carts on the other.  This arrangement usually works out well.  On even larger shoots, you may have a mobile home for wardrobe and hair/makeup.

LOSS / DAMAGE

Something donated will get destroyed or soiled and you'll have to pay for it.  Don't count on being able to return all your buy-and-returns - some of your cast members will probably ask to keep a favorite item.  I usually let them (unless it was really expensive).  You can hold a wardrobe sale at the end to make back some money.

MISC. EXPENSES

I typically put $5-30/day * the number of shoot days for cleaning.  The range depends on the size of the wardrobe and whether we can use a free washer/dryer.

You'll need to buy expendables - lint rollers, plastic bags, shoe polish, tape, safety pins, and paper/toner if you're printing continuity photos.