CNY is expensive enough already, so no need to buy things only to discover later you didn't need them. This I think is the minimal set that allows you to perform all the 点前 up to 四ヵ伝.
Until the student acquires a quality piece, the teacher should lend a quality-piece to the students. There is really no space in the world for plastic-made 棗 for practise. That means the 道具 has a box, a 仕服(しふく) and, ideally, a name.
My dream is that I end up with a version of all these tools that are Swiss-made
水屋
Sieve for tea
茶壷 filled with tea in Japan
Textiles
着物
帛紗
古帛紗 (you need four for 色紙建)
茶巾
大津袋 (even though you can even do 茶通箱 with just your 帛紗 and its a stupid thing to 拝見)
Wooden things
generally be able to make 桐箱
茶通箱
中付き
曲物水差
曲物建水
曲物水次
花盆
貴人台
茶杓 (with 仕服, so it can be used in 茶箱 and with 筒)
蓋置
茶筅 (in dark and light, with a 筒 for 茶箱)
短冊
水差 for 名水
柄杓 (that you can use on 台子)
Lacquered things
茶箱
棗 (including 仕服, so it can be used in 茶箱)
平棗
千年盆
四方盆
ふちだか
台子 (where you can use the top part as a 長板)
Ceramics
天目 (with 仕服 and 台)
貴人茶碗 (which fits into or around 天目, then they can be used for 重ね茶碗 or 茶箱
茶入 (with its 盆): ぼんりん, かたつぎ, だいかい
茶箱-set (with cords to go around the sweets container)
おうひ茶碗 (maybe 半筒)
織部茶碗
皆具 (especially for 蓋置)
せと水差
Metal
鉄瓶 made from silver
飾り火箸
花入
建水
釜 (雲龍)
かん
chains
風呂 (I like the ちょうせん one, but it's not very flexible; same for the やすれ)
Others
香合 (some sound related shape; akin to 利休's 瑠璃雀香合(るり すずめ))
干菓子盆
elevated 盆 for 貴人
タバコ盆
掛け軸 (probably 無感情)
象牙茶杓
香 itself, wood for summer and 練香 for winter
炭斗, I like the gourd one
ash spoons
ash
feather
Sets of 10
This is just a fun exercise for me to search for canonical 道具
Ideally, you'd start with one proper item for each slot; for 炉 and 風炉.
Then you expand into 真, 行, 草
Then you expand into the four seasons
Then you find one for each of the 12 months
Such 道具 would be 釜, 棚, 棗, maybe 茶入; 軸, 蓋置.
茶杓
They are not so seasonal by their shape, but with their fixed 御名. However, certain woods could be more seasonal, like 梅 for February and 桜 for March
I guess also a sooty bamboo one might be quite suitable for October.
You need to have one 真, so either a bamboo one 節無 or an ivory (which, today, means horn)
Theoretically, you also need a 元節; but you can use it officially for one 点前 only.
You could add one with several nodes for particularly auspicious moments.
I like the idea of having a set of 梅, 桜 and 松 wood; which, especially here in Switzerland, should be easier to make.
Scrolls
射座喫茶
常楽我浄 (Eternal, joyous, selfless, pure)
薄茶器
Riyku black (shin, works always)
Gengensais hira natsume (for autumn)
A high natsume, I like the one with the kawasemi that I have (summer)
Hinomaru (for NY, for doll's festival?)
fubuki (for winter, for sakura season)
nakatsugi in wood
zencha
kinrinji (I have one with chestnuts, also for autumn)
shiteki (I got the well one)
oimatsu (also for autumn)
Consumables
When the season changes, replace:
Fukusa
Hishaku
Futaoki (cut new one)
For a new 茶事:
Tabi
Chasen
Chakin
Chopsticks, 蓋置
Kaishi
I'd like to have a consumable drawer, where I could keep: