Screen Blinks on and off

My KDS50A2000 turns on. The picture will stay on for 1-3 seconds then go black for about 30 seconds. It will cycle through that rotation. I've tried resetting the tv, checked the bulb hook-up, did a power reset, tried different outlets and different inputs. All of these had the same result. I called two Sony service stores and they said it could be a small part that would cost around 200-300 or a light engine which would be out of my price range. I'd like more ideas before I commit to driving an hour or two for service or buying a new tv.