The Basic Guides to Male and Female Clothing include some general, gender-specific accessories. Most of these accessories are more historical than specifically steampunk. Here are a variety of common items included in steampunk costuming, helping to answer the question: "Do I look steampunk enough?" (Incidentally, the answer to that question is always "yes," regardless of accessories.
Read more: First Rule of Steampunk: There Are No Rules of Steampunk
Goggles
Goggles are probably the most popular accessory out there. Nothing says steampunk like a pair of goggles. You can wear them on your eyes, around your neck, propped up over your forehead, or strapped around a hat. Designs vary from actual, functional goggles to fashion goggles made for costuming. Fashion goggles start at about $20 but can get as least as high $100.
Monocle
Sometimes referred to as a mono-goggle, the monocle is an eye-piece that fits over one eye instead of both eyes. In most cases the monocle is simply half of a goggle. The historical monocle, which is a simple circular lens placed over the eye, is hardly ever used.
Tinted Glasses
Lenses are often, but not always, round. They are particularly popular around Halloween and in costuming stores. Prices start at about $7.
Jeweler Lenses
These are two small, circle lenses on arms that in turn can be clipped to a pair of glasses, goggles, or monocle. They run about $5-$10 a pair. Some steampunk stores also sell custom lenses which feature metal overlays and/or colored lenses. These have an additional cost.
Cane
A shaft of wood or metal with a decorative handle used by people of distinction. With your arm hanging straight down, measure the distance between your hand and the floor. That should be the length of your cane.
A longer version is a walking stick. A rugged, practical design would suggest an outdoor explorer. And more ornate stick would be for the upper-class, particularly women.
Pocket Watch
They come in wind-up and battery-powered versions. While the wind-up ones require you to wind it up regularly, some models allow you to see the complex internal gears, which are largely absent on battery-powered models. Prices start around $8 on eBay.
Bracer
A wide leather cuff that encloses the wrist, these can be worn alone or in pairs. They are often decorated with a collection of wires, buttons and devices, in which case only one is generally worn..
Pouches and satchels
If you're an engineer, you need a place for tools. If you're an adventurer, you need a place for artifacts and equipment. Everyone else needs somewhere to hide their wallet and cellphone.
Belts and Straps
You're going to need something to hold those pouches. Belts are most commonly of leather or leather-like material. Thrift stores often have a considerable selection of appropriate designs for only a couple dollars.