Thats a coincidence, I am setting up a 40 Breeder as well, it will be my first Saltwater tank, but I have been doing FW for my whole life. I am getting a bunch of stuff from a friend who is giving me a drilled 40 Breeder w/overflow and bulkhead , Prizm skimmer (not ideal but it is free) a PC light fixture, some live Rock, and some sand. I have built the stand already, and have put baffles in a 10g for a sump. I have test kits for Ammonia Nitrate, Nitrite, Calcium, phosphate and CH.
I plan on using RO water to start off, a shrimp, some snails, crabs, and other inverts and put in 1 or 2 clownfish to start from there idk but maybe some soft corals and we will see what else. This is all speculating though.
Keep me informed on how yours is going. Good Luck!