I've been pretty obsessed with Thai food since I visited Thailand in 1982. I have many of the thing listed at hand, and am lucky to have so many Asian markets nearby in the greater NYC metro area.. More specifically the neighborhoods of Woodside, and Elmhurst in Queens have large Thai and Lao populations, and Thai specific supermarkets... With online shopping you can get everything you need also...
I have found palm sugar in of all places Target.
And you should grow as many of the fresh veggies herbs etc as you can.. I have a Kaffir Lime trees which is about years old now, and even in NY and living inside for the winter I'v had it bear fruit.. currently I have Lemongrass, Thai and Holy basil, garlic and Thai peppers in my garden. The nurseries around me usually carny the various variety of basils, and lemon grass.... and cilantro is a given..
Also a sauce that hasn't been mentioned is "Golden Mountain Sauce" peek in to any Thai restaurant kitchen around here and you'll see a bottle..its like soy suace, but has a thicker body.
And if you really get into it and go down the rabbit hole.. get a sticky rice
https://www.amazon.com/Sticky-Rice-Steamer-Pot-Basket/dp/B00019MRRE
