I searched this website looking for a comprehensive website buying contract and couldn't find one. Maybe it is here, and I overlooked it. If it is, my apologies. Since I couldn't find one, I decided to cobble one together. The contract incorporates a number of provisions of Clinton's found in another post of this subject as well as a few others I found on the web.
Of course, this isn't the end all, or be all of website contracts. I'm not a lawyer, this is not legal advice. (Usual disclaimers, yada, yada) Therefore, use it at your own risk.
If you're unsure go hire an attorney. (Then post your contract here so we can use it!)
I hope this helps,