I will provide my expertise.  The Students need to purchase or bring the following materials:  
 1)  Drawing paper.  A white drawing paper tablet (found online on Amazon, or dickblick.com or Target) will work great.  I prefer 80 lb. weight paper, so I think the paper at Target might be lighter weight, but it's certainly fine if that's all you can get right now.  81/2 x11" or 9x12".   Strathmore has a 9x12 60-sheet spiral pad in 64lb. weight at Target for $6.49.  Also - "Mellisa and Doug" Drawing pad 50 sheets heavy weight on Amazon for $2.99.  Just be careful that it's not too stiff like card stock.  2)  A Pencil - Bic #2 mechanical 0.7 pencils from Target are my "go-to" pencils.  BIC X-TRA LIFE.  A 40 count box is about $10 but you can buy single pencils.  I create significant art using these and they're way cheaper than drawing pencils, but easy, since you don't have to sharpen them.  If all you have available are Ticonderoga #2, that's fine.  But I will not let the students use the pink eraser on the end of that type of pencil.  It smears the drawing and leaves a pink streak.  3)  An eraser.  White Pearl is fine..Target 3-pack $1.99  4) an Ultra Fine black Sharpie.  2-ct. $1.89 or 4 ct. $3.89 All these things can be found at Target.   5) The students will also need Colored pencils, and if Prismacolor colored pencils are not in your budget, (don't worry they aren't in everyone's budgets), then Crayola is the best bet.  They work fine for a class like this.  Also at Target - 24 ct. $2.99.    **** Additional! - gel pens* for the final decorations.  *Gel pens are optional  - Uniball Signo white can be found on Amazon. (highest ratings)