First one I saw looks like it can be bought as an option at a GM dealer: SONIC MCS COMBINATION SET 1/4", 1/2", 94-PCS 309402.
Runs $180 on EBay, about double that new.
Next one I found, which has a better selection of screwdriver bits is Vigor by Hazet V2461 Socket Wrench Set, Ratchet Box Tool...