i have little to no experience with most of these stores, i'm mostly relaying what i know through word of mouth. i personally thrift most of my wardrobe and then alter it, and for accessories, i either diy them or there are leatherworkers at markets in my city that sell things like chokers, cuffs and belts for very fair prices. i know fantasmagoria carries well known brands like killstar, punk rave, and devil fashion. draculaclothing ive also never bought from, but based on their images and some reverse google image searching, it looks fairly reputable. some people have recommended disturbia to me, but that looks to be veering more into the fast-fashion territory and a lot of the clothing looks both overpriced and low quality. everything ive just mentioned is totally out of my price range atm so i can't personally reccommend them, but it's what i know of.
you could also try to see if there are local small brands around alternative events in your area. i don't know if this is a thing anywhere else, but where i live local goth clothing brands (that have maybe 2 or 3 people behind them) organize markets to sell and advertise their goods.
but like i said, for my budget what's easier for me is diy. you can find grommets at sewing stores, sometimes they sell spikes and studs there as well but you might have to check in jewelry craft stores, thats where i get mine. it really depends of course on your style and what you want to achieve with it too, but for me diy is the way to go. i just feel like its way cooler and more fun to wear something i made/altered. theres tons of tutorials online too and many that dont require sewing, but i personally think sewing isnt even that hard XP
as far as white foundation goes i'm not really a makeup expert. i know sunset makeup has really opaque white foundation, but theyre based in the us, so ive never gotten it... and since im not looking for full coverage anyway i usually make do with a sheer layer of halloween facepaint
anyway! hope that was a little bit helpful, at least... good luck on your alt fashion journey!!