I would also include in your quote the number of proofs you will be providing for that price; after which, you will begin charging an hourly rate for any subsequent proofs. I've found this helps the client focus a bit more on their responsibilities, and it avoids making me into a victim of endless proofing. I usually provide 3 proofs in my estimate.
I also include the following statement on my proof sheets, which they must sign (my company name is SIGMA):
Every attempt is made to ensure accuracy in this project. This is your opportunity as the client to make alterations / corrections. It is the client’s responsibility to carefully check each proof.
SIGMA IS NOT RESPONSIBLE FOR ERRORS NOT INDICATED ON PROOFS.
Unless otherwise stated (via contract or letter of agreement), all original artwork, photography, layout files, and proofs created by SIGMA remain property of SIGMA. Unauthorized use is prohibited.
Last night I slept like a baby: I wore a diaper.