This is what we use when buying used stuff. It's modified from the form the DMV uses when you want to sell your used car. So I assume the wording is good enough.
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Bill of Sale
Merchandise(s) for Sale: ___________________________________________________
For the Sum of __________________________________________________________
The receipt of which hereby acknowledged, I did sell this subject merchandise(s) to:
___________________________________________________________________
On the _________ day of ______________________ , 20______ .
I hereby certify (1) The selling price shown is true and correct, (2) I am the lawful owner, (3) I have the right to sell the subject merchandise(s), (4) I guarantee and defend the title to the merchandise(s) I sold against the claims and demands of any and all persons arising prior to this date, and (5) The said merchandise(s) is free of all liens and encumbrances.
Seller’s name: ___________________________________________________________
Address: _______________________________________________________________
City: ___________________________________ State: __________ Zip: ____________
Telephone: (Home) ________________________ (Cell) __________________________
California Driver License #: ________________________, Valid till: _______________
Seller acknowledged receipt of payment in full:
Seller signed: _______________________________ Date: ______________________
Co-Seller signed: _____________________________ Date: ______________________
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Anyway, besides providing a receipt it'll protect you from the cops if you inadvertenly buy stolen goods. I just served as an expert witness in a case where the defendent bought a 5 year old laptop for $200 and was caught when he resold. The defendent claimed he did not know it was stolen and the prosecution said he did because of how low he bought it for. They argued that because he resold it for a lot more than he paid for (isn't that how capitalism works?--buy low, sell high), that he knew its real value was much higher and therefore he should have known it was stolen. To make a long story short, the defendent won because of my testimony. But I found it sad at how much the court system cost. My time and testimony cost the public defenders office $1,000.00 and I can only imagine the other costs to accured by the court and the cop who took a day off (I'm sure it was a paid day off) to give testimony. All this over a $100 POS used laptop.