For sure you can get keycap sets on AliExpress - I have ordered several.
It might be best for you to start with a small order of something, maybe a $20 clone set, to make sure they can deliver properly to you.
AliExpress sells competitively-priced keycaps under brand names such as Shenpo, JC Studio, Domikey, and others. Aifei makes the fake GMK sets, which are spotty in quality, among the least QC of these manufacturers. The best quality for the $ comes from JC Studio, which is unbeatable in the West at AliExpress (sale) prices.
The best "bang for the buck" are the fake Pyga sets, which may well be an Aifei product, but offer incredible value for a 135+ keycap set at $20 during sales.
You can also find unusual profiles. Not just the regular SA clones by Domikey and others. But MG profile [a Topre-like profile], AF SA [shortened Topre-like], and CX SA [a kind of spherical, angled OEM]. Plus many MDA / XDA copies.
It all depends what you are looking for. There are budget-tier and mid-tier available. But can you buy from AliExpress? Sure.