This is in no particular order.
I discovered this site whilst desperately looking for a UK based seller of NYX products. The range of NYX and other brands such as Sigma, Michael Todd, Mac and other high-end brand products on offer is extensive and the pricing very reasonable. Whenever I have browsed the site there have always been products on offer and I emailed them recently since they are very close to where I live and they are opening to the public next month! Also in the same contacts section you can request products for them to get in stock, although not having tried this I am not sure how they do on that.
I found this website when I was searching for cheaper Smashbox products. They also have a whole range of other brands. The pricing is cheaper than buying directly or from a department store, but still falls in the more pricy of the websites I am naming. With regard to Smashbox, they offer foundation samples for £1, giving you a chance to test before you fork out for the whole thing. They were very prompt with delivery when I ordered, and they always seem to have offers for free gifts with purchase.
Might be a surprise to some but I have always found great deals on hair styling tools on amazon (they even have the odd beauty products on there). Worth having a quick browse before deciding where to buy, and a lot of the time you can get free delivery or its very cheap.
This is on the list purely for their 30 day money back guarantee. It is the only place I know of where you can buy something, use it and send it back without even having to explain yourself, great seen as you don’t have the opportunity for colour matching when it comes to cosmetics. They also have some great deals where you can get a whole selection of products for very good value. The range of brands is extensive and they also sell hair styling tools and products and nail polishes.
I hope this is helpful to someone. Let me know your thoughts and experiences if you do go ahead with any purchases. I’ll be sure to update this post with any other useful websites!