Hello, I know this is an older post but I just had this same problem with my turn signals working on and off. I figured out it was my flasher/Hazard button part because if they stopped working and I slapped the hazards on and jarred the unit then the turn signals would start working again.
Also you do not need to remove the dash to change this part. Simple take a flat head screw drive and pry the hazzad button off. This will break the old switch but it will expose the part so you can get it out. Take the same Medium size flat head and slide it next to the switch at the 4 o'clock position, take a needle nose and grab the switch in the middle. By pulling on the switch and wedging the screw driver between the dash and the switch you will be able to release one side of the switch from the dash. Now without letting go of the switch with the needle nose, take the screw driver and wedge it in at the 11 o'clock position. This will release the other side of the switch. Give it a pull and the whole thing will come out of the dash. Disconnect the wires via the plug being careful not to let the wires pull back into the dash and plug in new switch. Then simply slide switch in the opening and it will click into place, good as new!!
This is much easier than taking off the entire dash. It took me 20 minutes to figure this all out and do it on my car. If I did it again it wouldn't take me 5 minutes. hope this helps anyone with this problem.
As for the part, it is a direct GM part so there are no aftermarkets as for now. I went down to the dealer and bought it for $50 but you can get it cheaper through
www.gmpartsdirect.com for $38 including shipping. The GM Part number is #10359031. Okay well Good Luck!