It seems like your dealer is going to replace a bit of parts, regardless of their condition, not sure if this is because they truely need to be done or becuase he has done a bit of work and knows that over time they too will need replacement. Sometimes it is easier to do all the work now, instead of as it goes, but that is a bit of money and I agree, I would not want to replace perfectly good parts without justification.
On the other hand, a lower unit is not something to fool with, it can ruin your season if there is water in it. Whatever you decide to do, make sure the source of the leak is targeted and fixed, and that anything that may have been damaged was fixed. Not sure if you change your own lower unit oil, I do it myself and can tell by the color of what comes out if things may need a looking or not. I'm sure the dealer has long thrown out the lower unit oil from your engine, but seeing tht would have been the best source you could have to determine if he is riping you off or if you truely need the repairs. Some engines are caught before damage really occurs, so it may only require seals and smaller parts which can be done by anyone that is very handy, although personally I leave that to a mechanic because I would rather them be responsible. If there was a bit fo water in your lower unit, the lower unit oil would be very discolored, have water seperating from the oil, and even possibly some metal shards. If this is the case, then more then likely you would need a bit or repairs or even a reuild.
I'm not familiar with what work has been done on your particular engine, but given the year of it, there is a chance it may need some repairs to it, but it may not require a full rebuild.
If you are going to the dealer and he has the engine apart, have him show you whats worn down and might break, I know you are probably not familiar with what the parts look like, but you can often see a worn part when shown one.
I guess the only real piece of info you can go by is asking th color of the oil that was removed. If it was clear and slightly hazed with a small amount of oil, it is probably just seals and has not done enough damage to justify a rebuild. If it is clear with no water, he is ripping you off big time, but I almost guarentee no dealer would tell you you need work done to a lower unit and tell you your oil is good. If the lower unit oil is black and had some metal scraps, I'd think about doing some work, maybe not a full rebuild, but that is a tell tale sign of parts wearing and that you should really think about having a bit of work done.
