Mitsubishi Lancer braking vibrations

2002 Mitsubishi Lancer Oz Rally, Approx. 68,000 miles.

I experience vibrations or pulsating, accompanied by a low rumbling noise, while braking over 40 mph. While i'm cruising there is only a very slight vibration around 80 mph but it does not make noise or feel the same. The braking vibrations come up the steering wheel, through the brake pedal, and through the seats. I have had my front rotors replaced twice (the first set were warped), the rear drums smoothed off, new brake pads, a wheel balance, and a brake kit put on (I think the mechanic described the brake kit as new seals, etc. In the lines). Anyway, after a month's worth of work I feel the vibrations as soon as I drive out of the shop. What else could this be caused by? A friend suggested the wheel bearings, and the mechanic suggested it was worn tires. Would either of those cause vibrations only while braking?