Kudos to you for getting info before the little guy is actually in your home and Congrats!

For food variety is a good idea. You do not want to buy bulk food, since it can go rancid quickly and then your bird won't eat it anyway and it would be a waste of money, plus you may get moths. Hopefully you already know an all seed diet is not good for them, so keep on the lookout for some seed and pellets that are NOT artificially colored, flavored, or preserved-Harrison's and Roudybush are good brands. Get plenty of fresh, organic veggies, and some fruits. You can also offer them whole grain pasta, brown rice, quinoa, wheatgrass, etc.
Be sure to give them toys that will stimulate them, like shreddable soft wood kabobs, or things to forage in.
Chemicals from candles, perfumes, markers, glue, pretty much any smelly thing can be toxic to them. If you refuse to do away with them, only use them far away in other rooms and make sure your home is well ventilated.
Concrete perches are good for filing down their nails & beak, so you don't have to trim them.
I highly recommend a book called Getting Started Clicker Training For Birds by Melinda Johnson. Tells you everything you need to know about birdy behavior and how to get them to do what you want.
Other items to consider getting would be a cage cover (can be a clean sheet), styptic powder, bird-safe cleanser (such as distilled white vinegar, Method Go Naked, or 7th Generation) to clean cage & toys, nail clippers, bells, swing, ladder, stainless steel food & water dishes or a glass drinking bottle, perches of different materials and sizes (but
not sandpaper ones), a humidifier, an Avian sun lamp, play gym(s), bottled water, and emergency kit, and pet insurance (or start an emergency fund).