Ok basically anything 'brand name', don't buy it on Aliexpress. Doll clothes, wigs, accessories, those are totally fine to buy on there but unless you 100% KNOW the doll company is the one selling the dolls on there (highly unlikely) then just don't buy. Aliexpress is an offshoot of Alibaba which is a bulk ordering site for inexpensive, mass produced goods made in Asia. Not exactly what I'd want in a doll.
Plus, even if you are buying with the knowledge that it is fake, it does hurt the company and you are also paying for something severely lacking in quality. I've seen recasts. They are just plain not up to snuff. They have thinner resin, rougher casting, lower quality resin, and I've even seen instances of parts drooping and warping because the resin wasn't properly cured. If that last part doesn't throw off a huuuuuuuge warning sign to you, improperly cured resin can be really really toxic and could still be putting off really bad fumes into your house. I don't know about you guys but I'd rather save up for longer for a legit doll than end up with lung or brain damage.