Tools and Notions

Wawak - Sewing and Dry Cleaning shop supplies.

Kam Snaps - Plastic and metal snaps and the tools to install them.

Amazon.com - There are lots of options to get supplies on Amazon. Though, I can't vouch for the quality of all the vendors on Amazon.

Fabric

Sy Fabrics - They have a bunch of staples. It's my go-to source for satin, spandex fabric, stretch velvet, lace, and jersey knit.  Fast shipping. Lots of swatch options too.

Denver Fabrics - Good selection of fabrics from overstocks to reorderable. They even sell some by the bolt. (Same selection as Fashion Fabrics Club.)

Online Fabric Store - Decent source for staples. Indoor and Outdoor fabrics are available.

Hardware and Decorations

Michael's - If you don't have a Michael's near you, their online store is decent and they have fast shipping.

Etsy - I have found great options for belts, buckles, zippers, and fabric.

Studs and Spikes - Nice variety of prong and screw-type studs (and spikes).

Pacific Trimming - Good selection of bag hardware.

Emmaline Bags - Excellent source for bag making patterns and supplies.

Bra Making Supplies

Sew Sassy Fabrics - Bra and Lingerie fabrics and hardware including underwires, fasteners, and patterns.

Bra-makers Supply - Good patterns, fabric and hardware for bras and lingerie.

Farthingales Corset Making Supplies - They specialize in corsets, boning, eyelets, hooks. I really like their eyelets.

Business Resources

These are affiliate links. If you use them, I may get a small payback, but it will cost you nothing. 

SmarterASP.net - Web Hosting (.Net Framework and WordPress)

Flodesk.com - Email Marketing