fasttech is great if you make sure that everything you want is in stock and shipping doesn't take that long through any of the $2 upgraded mail options.
The problem is when you want something that is restocking in 5 days or 7 days etc... You put all your chosen items in your cart but there a few that ship in 7 days. The order sits and waits till the restocking items show up. When that item shows up they fill your order and off it goes.
If it is a popular item and they only get 500 in and you are number 501 in the queue you sit and wait till the next restocking. Meanwhile if they need something from your order to finish another order and you have items waiting for restocking, they will take the item they need and you will go back in the queue for that item as well.
Only populate you cart and place your order when all items are listed as in stock or ship next day. Otherwise leave them in your Wish List till all they are in stock, then add all to the cart and place your order.
I have bought quite a few things from FT without issue.
If it says Authentic then it is, If it says Style than its a clone. Check the Reviews and mostly the Discussion section for information on the quality of the product.
Here is an Authentic Subtank Mini that is a real Kangertech product for $33.33
https://www.fasttech.com/products/0/10004861/2106401-authentic-kangertech-subtank-mini-clearomizer
Here is the clone without any logo's for $21.13, notice the Styled in the title.
https://www.fasttech.com/products/0/10012000/2129501-subtank-mini-styled-bdc-bottom-dual-coil
Be very very leery of any RDA that has a gold plated deck, it flakes off in tiny pieces which you could inhale by accident, Chinese gold plating leaves a lot to be desired.If you stick with Stainless Steel you will not have that issue. The big problem with a lot of the clones is the machining, the threads can be very rough and there can be a lot of burrs and machine oil on the product. Always totally disassemble all products and a good wash and clean out.
IMHO there is not any reason to buy an authentic item from Fasttech, you only save a few dollars and have to wait for the product. Buy the authentic items from your local B&M.
If you are looking to buy something to try out such as the Magma RDA from Paradigm Modz, you can order an authentic online for $115 from any reputable vape shop or you can pick up a
1:1 clone from FT for $15.79 to see if you like it or not.
It's hit or miss with FT if the product will be great or junk, there are quite a few 1:1 clones there that are actually better than the original but YMMV.