Yeah, pulling an automatic is a bitch. I've done it a few times, and never enjoyed the process. You have to disconnect the cooler lines which means it's going to loose some fluid. I'd try and get as much done for that price as you can. If they do a complete fluid change on the transmission including dumping out the converter it might be worth it. That price seems a little on the high side, but not wholly unreasonable. There is no clutch to get full of oil, so the seal leak is simply a nuisance. If it's only leaking a little bit, you might just want to ignore it.
Kurt