There's nothing like wood. We've long looked for simple wood frames with GLASS that we could use as a sort of house-frame to hang all our art. We also wanted them to be affordable. We finally stumbled on MTS frames at the Pearl Frame Shop and now buy them in quantity directly from the manufacturer for our clients (much cheaper).
Our favorites are the classic bright white wood and the black wood frames ($9 for 5x7 to $75 for 30x40 - really big). They also come in a thin (13/16) frame and a deeper (1 3/8) museum style frame. These are very popular at Pearl, and they go in and out of stock, so a quick phone call is advised before you make the trip.
(Re-edited from 2006-01-17 - MGR)