There are battery-powered mittens and gloves, found usually at hunting-supply stores. Cost is about $50. They work, but are bulky and not terribly effective. You might also try any gloves made with the fabric called Outlast. It's a heat-distributing material, originally used as insulation in the space program, that literally stores warmth when your hand is warm and releases it when needed. I have several Outlast gloves that I use when cycling, and I love them. I think they'd work well for Reynaud's sufferers as well. Performance, the online bike dealer, makes a pair of Outlast gloves called the Outlast Thermal Glove. They're on sale for $35, and would make a great heavy liner glove under a shell. I have a pair and they're also very warm on their own.
Still, a really good solution is on the horizon. A year ago, Polartec introduced a new fabric called Heat, which has very fine metal wires woven with fleece. When given some electricity from a few batteries, this material heats evenly and quickly. Heat now can be found in the Met5 jacket from The North Face and heated blankets from Lands' End. I don't think it will be long before it finds its way into gloves, and they'll be terrific.