Welcome to chickens!

My advice would be to not buy too much beyond the basics at first because your needs will probably change as you go.
*Appropriately sized secure coop - we started with a 4x6 coop for 6 chickens and added a second 8x10 coop the next year

*Appropriately sized secure run - added onto the secure run 3x in 3 years and built a extra large semi-secure daytime run.
*Feeders - we started with chick feeders, bumped up to 5 gallon buckets with feeding ports (worked well until we got more chickens), switched to hanging gravity feeders and ended up placing those in rubber feed pans to keep food from being spread all over the run.
*Waterers - started with chick waterers, switched to auto filling cups (6 out of 7 failed over the next several months either by not filling or over filling and flooding the run). We now use rubber feed pans except when we have a broody with chicks then we use gravity feed drinkers for a few weeks. We don't use those all the time because my flock likes to constantly kick bedding into them
*Food - you can't go wrong with a good all flock that anyone can eat *Heat source for chicks - we have used a heat lamp - has safety issues, a brooder plate- broke after the second batch of chicks

, and a heating pad brooder plate which worked well this year
*Grit - you will need chick grit at first and then adult grit
*Corid - if you have to order it, have it on hand. I live about 15 minutes from a
Tractor Supply, so I just make sure they have several bottles in stock and then buy if needed.
I think, unless I have missed something, everything else can wait a little while and be bought as needed

. Oyster shell is a must once they start laying - I put it in a small hanging bird feeder so they can eat it as needed. Nesting boxes will depend upon your set up.