Unfortunately, it can be a pretty serious mismatch that just doesn't work out on paper very well. 

My previous custom chopper significantly upgraded his choppers and then went to not filling bags or silos because of it. I fully understood his math, and made a ground pile to get by with him for a year. He obviously didn't understand his client list though as he no longer chops silage. If he had owned a bagger that fit the scale of his output, maybe everything would have worked out. I would assume your client would be fairly understandable as he's asking for something extra on the side of the normal a pile, but maybe he expects you to have a bagger that more closely fits your flow.  

I filled three 9' bags this year. $2 per foot for the bagger and the man running it. I bought the bags, provided the tractor, and a skid loader w/ forks for bag set up.