I've always heard this. The weird thing is that if someone came in off of the street they would have no idea if they were a mechanic or not. So basically it's 'ok' for everyone else but since they KNOW you are a mechanic you get hosed even though you work for the 'same' company.
Just don't tell them you were using them for work use, or tell them you were using them for personal use if they try to deny on commercial use, or go to another sears if you need a replacement. And what qualifies commercial use? Just being used in a work environment for company purpose? We had a mix of tools at my previous company, some Snap-on or the like and some craftsman. I bet we used them less and with much less abuse than some people use tools for personal use.
I've heard flea markets are also good places to get craftsman tools, especially mixed pieces to replace missing sockets. You can still get them replaced at a Sears since you don't need a receipt (as far as I know).