A beautiful blog by Paco Peralta, worth a gander... You'll have to click the "translate" button for English, but the images alone are pretty self-explanatory.
Fabrics
Rosen and Chadick is a high quality, friendly New York City fabric store, with an extremely helpful and knowledgeable staff (a rarity, these days). If you know what you need, they can ship it to you. (Swatching available for a fee.)
Mary Jo's cloth store is a MOUNTAIN of fabric and notion choices in North Carolina, with quality e-commerce service, as well.
You can find stretch fabrics for costume, swimwear, dance and more at Spandex House. Located in Manhattan's garment district, they can ship whatever you need.
And why mess with perfection? This blog answers ALL of your fabric and notion sourcing questions easily.
Patterns
Patterns from the Past is a lovely e-commerce site, dedicated to selling vintage patterns for women, men and children.