When I think permaculture supplies, I first think of Home Resource, craigslist, free cycle, thrift stores, and other places I might get some materials for a good price. Home Resource, for example, has a whole store full of materials to inspire ideas using existing materials to create raised beds, trellis, windows, landscaping rocks, fencing, structures, greenhouses, etc... Otherwise, craigslist is a good source for free fill dirt, organic materials, outdoor furniture, and so many other things. Last year, we picked up an arbor, a deck, a table, chairs, display boards, and some straw bales that have all gone to use at the house.
The task of practicing permaculture in the winter is a good one. There is not a lot you can do in your yard during the winter. There are a few potted plants that can be grown in your window, but you otherwise have to rely on the canning and other stored foods you have from the previous harvest.
The winter months do give you an opportunity to plan for the upcoming season. Get your seeds ready, plan to tear up some grass, or bury it with
compost to open up some more available growing space. Also, read up on permaculture and check out the local presentations and forums to see what others have been doing. And as the pervious post mentioned, garden supply stores can be a great resource for ideas and supplies to get you started.