Good Advice would be to go to a wholesale factory that sells nylon mesh that you will need for your screen printing mesh, wood for your frame and various other attachments you will be needing for attaching the frame together.
If you were to shop around for the best prices that would be your best bet.
Screen Printing Supplies that you will be needing

• Nylon Mesh
• Wood strips measuring 8 1/2 x 11"
• staples to join the nylon over the wood.
  A staple gun is a good idea for this.
  
• water-resistant masking tape
• old newspapers to prevent mess
• water-based inks
• a piece of cardboard to insert inside a double layer of fabric such as a t-shirt or a cushion cover
• stencil of your design

The quick, easy way to build a frame This is a nice project for your kids to do in their vacation, what is more it does not cost a lot What they will need

• embroidery hoop
• nylon fabric
• squeegee
• water-based ink
• hod podge glue
• cardboard

Divide the embroidery hoop in two and insert the nylon material between the hoops.
Glue them together and cut away the excess material.
Leave it to dry.
Find a design that you like and trace it onto the screen Take the glue and paint where ever you would not want the ink to go on your shirt.
Place the cardboard inside the t-shirt otherwise it will seep through to the back Put the screen on top of the t-shirt Place a blob of paint on the screen and move it down in one action with an equal amount of pressure, making sure everything is covered.
Wash the screen in cold water.