I will buy tried and true products from fasttech.....meaning, you go to the first page and you know those are the most popular items (as in Kayfun 3.1 ES, Taifun GT, Nemesis, some RDA's etc..... and usually will have the rating stars in the hundreds to match how good they are. I will also buy dirt cheap replacement tanks for the afore mentioned toppers there, as well as drip tips, o-rings and general cheap stuff like that. Hard to beat. What I order from Fasttech are things that I dont need at the moment, but think I may like to try, or items that I may want several backups for.
I generally get my Mods and some original toppers from the US or Europe. I have also noticed that many venders have started selling some items such as the MVP 2 as cheap as FT, so thats a good trend for the consumer in general.
All of my DIY supplies come from the US.
I buy AW batteries and there is one seller in particular that only sells the Newer Silver hologram logo batteries..... Example, 2000 Mah 18650 4 for 27 bucks free shipping (ordered some of those and some 350's today as a matter of fact..