Gesswein - I like Gesswein’s products. I always get what I ask for, with no hassle and they offer products that Rio may not carry. There are three big problems with them though: 1. Their website stinks. I can never find anything with their search engine. It is also difficult to find things via their site in general. 2. They take a bit longer than Rio Grande in shipping out their merchandise. 3. Their site is very slow to load and their search engine is slow. Other than those three points, I stand behind them.
Koil Kutter - Dave Arens has created this great method for cutting jump rings. It will cut Silver, Sterling, Brass, Bronze, Gold and Copper. He also has a few other products available. You can only contact him via email which is: firstname.lastname@example.org.
Metalliferous - Big metal supplier. Lots of different shapes, sizes and thicknesses of sheet, wire, tubing, etc. Copper and brass stampings, nuts and bolts and other strange things are available here. Some of them I don’t get (like this) but, hey, it’s not my store! Always get what I ask for and they are efficient. Good PDF online catalog.
Otto Frei - Metal, Tools, Materials, Findings. Otto Frei offers many different tools and materials that are not available at Rio Grande. The people who work there are great
Reactive Metals - Get your Niobium, Titanium, Anodizers, Mokume Gane, Bi-Metal, Alloys, Patinas, Nuts and Bolts, Taps and Dies, Drill bits and these cool silver things they call Impressions (page 15) here and so much more. It’s a fun place to shop and explore. PDF online catalog.
Rio Grande - Sheet Metal, Gems, Tools, you name it. My main supplier because of their great prices, easily navigable website, great customer service and excellent shipping and turnaround times. The only complaints that I have are that they have limited tubing and wire selections and not much of a choice in copper/brass or bronze metals.
Keep your eyes open for a Blacksmith’s Cone Anvil – I have one and love it – it’s my main forging tool for round shapes. Haven’t checked this links out and it’s smaller, by far, than the one I own. But, this is all that I’ve found so far.