Markertek and Redco are two of the more popular ones that I'm aware of, at least on the eastern side of the US (both in the eastern NY/CT area).
For connectors, they Neutrik NC3MX (male) and NC3FX (female) are basically your ubiquitous XLR connectors. They're inexpensive and easy to solder due to having cups to hold the wires in place. Just make sure you put the chuck and the strain relief on the cable before you solder the connector on! Switchcraft XLR connectors are also very common, but I've read that they're a bit more difficult to work with (can't confirm or deny this though, as I've only ever worked with the Neutriks).
For cable, you can get good cable made by Mogami, Canare or Belden. Your Mogami cables probably are made with their 2534 quad cable, which just means that it has two conductors each to connect to pins 2 and 3 (instead of just one conductor). Canare Starquad is another popular quad cable. Quad is slightly more of a hassle to work with but not prohibitively so. I made my mic cables with the Neutrik connectors and Canare L-2T2S cable which is a standard two-conductor cable instead of a quad, but one day I lucked out and found on eBay someone selling 300 or so feet of mic cables handmade to various lengths using Mogami 2534 and Neutrik connectors. I think I paid $150 for the lot or something ridiculous like that, so that kind of set me up for mic cables.
If you want to make XLR-TRS cables (every studio needs them), Neutrik's NP3C is an excellent TRS connector that's easy to work with.
Oh yeah...my favorite thing about making your own cables? The variety of colors you can get them in. Useful for color coding cables by length or use, or just for something more interesting to look at then dull black cables.