My rule of thumb: If I sell any names to someone who is willing to pay by PayPal - I always push only after money successfully withdrawn to my bank account. Usually takes 2-3 business days.
It is my understanding that this will not protect you - I have been told that they will put a stop on any money in the account and they can also draw from the bank account associated with your paypal account if you have no fund in your account... so in effect any funds you have in paypal or bank can be held while paypal works out the dispute.
Im surprised that no company has set up for low cost domain sales.(under $100)
I have a dispute that is likely to turn into a claim any day now with paypal. I pushed a domain from my namecheap account to another a month ago - the buyer now cant find it. I have armed myself with whois screen shots, a conformation letter from namecheap stating it left my account and arrived in his but I doubt that I will win if it comes to a claim. Id be more than happy to pay a company to protect my small sales if there was one. I also think if paypal accepts payments for domains then they need to reassess their protection for domain sales.