Contracts

Is a hand written and signed bill of sale (by both parties) and not notarized acceptable in the court of law. Are there any states where a bill of sale is not acceptable in court unless it is notarized? In particular, will a non-notarized bill of sale be acceptable in Arizona's courts?

What constitutes a legal buyer and seller contract on eBay.com? What can be done when you are the highest bidder and eBay notifices you of the fact and then closed the bidding and you are not able to contact the buyer nor will eBay give you a sound reason, except to go to this site or that site?

I promised to buy my niece a car if she passes the bar exam. She was exultant over how easy the exam was and assured me that she passed so I brought her the car. When the results were announce, she did not pass. Now that I asked her to return the car, she refuses stating there is no contract binding her to return the car. What can I do?

If I have a dispute with a car dealer on the repair work of a used vehicle I have agreed to purchase, can I cancel the contract/sale all together if it has been within a month's time?

Do I need to contact an attorney before signing a release and trust agreement from an insurance company?