Did you say that your current tractor also had a 300cx loader? I didn't think those would fit. IF so, you could just keep it and use it on the new tractor.
Anyway, I to think that is high. I bought a 3520 with a 300X ehydro for 21K brand new with 0% interest. That was a few years ago, but still.
Thats 20 grand for your extras.
I would low ball my counter offer and see where he ends up. Also, How long has he had the tractor on the lot, and does he have any low hour 2000 series tractors on his lot. That will make a difference.
When I traded my 3520 for my 5083E, the dealer had been sitting on the 5 series for a while and had no good clean used compact tractors to sell to all the hobby farmers around here, so he really wanted to trade, and gave me the best deal of 4 dealers I got quotes from. The reason was that the other dealers didn't want my little compact tractor as a trade.