Above is the simple wizard costume I made by over laying material. The first layer of green, and the cheapest, went over me like a big poncho with a hole for my head and I stapled up the sides and left large sleeves. The second, and more expensive material, went across my shoulders, down the front an back in a diamond shape. And with a bit more talent you could make a simple hood simular to the one in the pic of the devil costume above. This should give you the classic wizard look ala Gandelf.
My staff was made with one inch pvc. Cutting the top two feet in quarters, inserting the ball ( or skull or whatever) and tapping with duct tape and then adding a coupling and something for the top, then paint the color of your choice. A good looking tree branch makes a good staff also with a few decorations ( skulls, feathers, bells, bones, ect.)
Hope this helps a little.
you could take a black sheet or any color and wrap it around you tying it with rope or chain or big wide belt make a cheap hat with cardboard, felt and glue stars and moon made of felt or hot glue on it or use a witch hat and embellish that. here's a pic of a wizard hat some had at my last party ,they had a long white wig with it and long beard and a cheapo store bought robe costume...maybe it all came together as a set I don't know but making them is way more fun. I like the wood branch staff idea better myself ..those are real easy to make.
depending on what look you want you can add anything to hat
here is a staff i have but did not make this bought it at renaissance fair bout 12 yrs ago his name is goeshh
If so, there are some good patterns out there that aren't too difficult.
Thing is, cloaks require a lot of fabric - anywhere from 8-10 on average. However, if you check out your local JoAnn Fabrics, they always have a clearance section where you can pick up fabric cheap - around $2-5 per yard.
Here's an example of a few patterns (on the Simplicity link, just scroll part way down the page to see wizard cloaks):