My mechanic's charging $1000 for oil leaks caused by broken sealers ...is that fair or not? Please lemme know before I go to pay tomorrow.

which Im going to have to either way since i cant go a day without checking on my car

Where are the leaks? Rear main seal?

+1, if it is rear main seal then yes, most other things then no.

As mentioned for rear main yes trans has to be removed to get to it as well as torque converter an flywheel. Front seal i can see it being up there ... removing everything plus the crank pulley and such isnt such an easy job either but a grand seems high

But for most other things sounds a bit high to me

any oil leaks that are not lower oil pan related or valve cover will cost between 500-1500 in parts and labor on a W211 E63. I always recommend redoing all o-rings and seals if one begins. Any rubber if not changed will soon fail/leak if it has not already and best to do them all at once if they are of the same age. this will save you from paying for the same or similar labor months or a year later.