how much would it cost to replace a timing chain guide and possibly a lifter if it bent?

Goodness, this begs a conversation between you and a BMW capable technician near you. Use the repair shop locator to find a trusted shop near you. You certainly can't estimate that kind of work on this kind of vehicle from this site. Use this link to find some shops near you that can help with your concern: www.repairpal.com/repair-shops