Notary Public
I am very new at this. I am in the process of putting a house under contract. I got the purchase and sale agreement ready to go. I will be at the sellers house and he is ready to go ahead with the deal. I do not know if we need to go with a notary public or if the contract is valid without the notary's stamp. Another question about notaries: Should both parties be present in order for the notary to stamp the document? 
A contract does not need to be notarized to be valid. A lot of real estate changes hands every day under contracts that are not notarized.
If you feel some need to record your contract -- perhaps to cloud title -- a contract does need to be notarized if it is to be recorded. Rather than recording the contract itself, one suggestion I have read is to record a notarized "Memorandum of Agreement" instead.