I get all my base wood, probably more than I'll ever use, from carpenter friends. One fella works at a wood mill also. He gets some exotic wood, wood with strange grains that get cut out, and lots of pine to build small shelves bases and also use in my diorama's as scale lumber. So visit your contractor friend at his shop or at his next building site and see if he'll let you 'rummage' thru his scraps. Finishing Carpenter's get the best stuff.

I agree, my best bases have been odd off-cuts and scraps from various projects, shops and friends...
Garth