Generally a small kit is a 2x2 tent with a 100W LED light. The will be a number of combo kits with this on amazon - https://www.amazon.com/Spider-Farmer-Complete-SF-1000D-Spectrum/dp/B08L5VJ8FB for example.
If you want to DIY it, you can buy the pieces separately as needed. Already have a closet - skip the tent. Don't care about the smell - skip the carbon filter.
That would be about the cheapest I’d personally go for a complete kit. Good light and it’s got all you would need.
You can go super small and get a decent yield.
Check out r/spacebuckets they have some really neat ideas.
r/microgrowery is also another great resource
For about the price of an ounce you can get a full setup. I have this setup in a 3x3 but this will do perfectly for one plant at a time. If your grow goes well you can yield up to about six ounce or so per plant
https://www.amazon.com/dp/B08L5VJ8FB/ref=cm_sw_r_apan_glt_i_RH1BHSVRM5P7YMS9X5QH?psc=1
Using these will help your cure and storage process. Otherwise you'll likely get mold
Boveda 62% Humidor Packets - 2 Way Humidity Control Packs- Size 1 - 20 Count Resealable Bag - Cigar Humidor Accessories - Bulk Humidity Packs - Relative Humidity Packs - Humidor Packet https://www.amazon.com/dp/B07G8GC8TQ/ref=cm_sw_r_apan_glt_i_RVRM1KNY3B4A6Y5TRX57
You'll need a few things in addition as well. You'll need to decide what nutrients you're going to want to use, you'll need a bottle of CalMag, some pH up/down, and a pH test kit. All this will run you another 100-150 but will last you through probably tens years of growing if you run one plant at a time.
Feel free to ask more questions.