Ok time to put this story to bed. I picked up my lock today and it works fine. The total bill was $74 which is more than I expected , the labor rate is $92/hr (I didn't know this) and they charged me 3/4 hr labor. This is a lot less than this fiasco could of cost me so overall I'm happy and thanks to everyone on this site who helped.
Unfortunately the guy who fixed my lock wasn't there so I didn't find out the cause of the broken wafer or if it's common
Broken wafers are not common, but they do occur. The cause is usually due to them being forced with an incorrect key, or someone trying to force the lock with a screwdriver etc. I would suggest that this wouldn't happen if you (or previous owner?) left the stove knob in the cylinder all the time.
Regarding how much it cost to repair. I would never quote on a job like this. I would suggest our hourly rate and say that would probably cover it, but there is no way to really know what is going on until you get it apart. Especially when it is a cylinder I have never seen before. For example, I quoted a customer $600 to open their safe yesterday. I'm only going to bill them about $200, but I need to prepare them for the worst otherwise I could be wasting both our time.
Also, as the locksmith probably doesn't have access to replacement wafers (every manufacturer is different), your locksmith either simply left it out or modified another manufacturers wafer to fit yours (ie. filed it to fit).
