To get reasonably cheap material try the local markets. Spotlight and Lincraft are national fabric retailers. For more detailed information on what to look for when buying your fabric refer to the Fabrics and Colour section.
Your approximate fabric requirements are (based on 115cm wide fabric … beware as fabric comes both wider and narrower):
Pants: Twice your leg length plus extra for hems
Tunics: Double the desired length. If you want long sleeves get 1 metre extra
Fitted Dress: About 5 metres
Mantle: 2 metres, lining extra
Cloak: 3 to 8 metres depending on the height of the person and fullness of the cloak.