Buy the biggest crate you can find that comes with a crate divider for potty training. I would recommend toys that have no stuffing in them but squeak, rope toys, balls, treat dispenser toys for when he gets a little older. A cheap collar because he's going to grow out of it so quickly. An extension leash for potty time. A shorter leash for tethering him to you. A cheap bed if you want one for him. I'm saying cheap because more than likely he'll destroy them. Haha. If you can, buy some bitter apple spray for your wood furniture and invest in a good pair of shoes so he doesn't chew your toes off. Haha!
Also invest in some vicks vapor rub for your arms after he turns into a landshark (to be used as a bite/chew deterrent on YOUR skin, not his!). An x pen if you can afford it. Some blankets to put in the bottom of his crate (so you can switch them for washing if they get accidents on them)... I would also suggest nail clippers for right after you get him home if the breeder didn't already clip them - and to get him used to them as baby. Quick stopper powder just in case... I can't think of anything else. I use Wellness puppy food for large breeds. Sometimes petco has it on sale.