eBay.com is a collection of shops selling homemade items and resources for making homemade items. My suggestions here only scratch the surface. There's a lot of quality steampunk items to be found here. The shops do have a habit of disappearing, however. All external links will open in a new tab or window.
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Mr. Trendy Kin - Awesome pocket-watches for $8-$15. You simply can't beat that price. Most are mechanical, rather than battery-powered, so you'll have to wind them up about every 12 hours if you want them to actually tell time.
Canal Boat Trading - Fashion overbust corsets from about $20. Steel boned overbusts from $40. Underbusts also available.
Corsets Boulevard Ltd - Another extremely affordable corset shop, roughly comparable with Canal Boat.
Art Creations by Shir-Lee - A wide variety of feathers for decorative projects (particularly hats). I can personally attest to the quality of her product. I've been very happy with my purchases. $8 (including shipping) gets you a 60-70 feathers or a feather pad.