primative gatherings, the cotton patch (in East Tawas, MI),
eveningstar designs, fabric.com, sue spargo.com, and the local thrift stores
are all my favorite resources for wools. and wool is wonderful to play with dyeing fabrics, so if you are not finding the colors you want in the thrift shops consider dying your own.
marcus brothers puts out felted wool bundles- i think the pieces are something like 9"x11" in a variety of colors (solids) and hand dyes (mottled) i watch for sales on these because you get a number of great colors at a good price.
if you visit the marcus brothers site you can find out the shops that carry them - then visit those shops and find a couple that (catch your eye) then watch for sales. :thumbup: i love working with wool!