Ethically, I don’t see any problem in selling a car to a person with a suspended license. When you sell a car, it’s perfectly reasonable to assume the buyer will use it lawfully (that is, wait until she regains her license.) You have no responsibility for controlling another adult’s actions. Besides, if your friend intends to buy a cheap car, she’s going to buy one; if not yours, then somebody else’s.
If you sold her the car, and later found out that she killed or seriously injured another person while driving it (illegally), would your conscience bother you?