I wrote back in 2016 about Feel Unique’s Pick ‘N’ Mix service and I’ve used it ever since (admittedly I have probably missed a few months here and there). The deal is that you can get 5 samples for £3.95 (free delivery) and you are then given a voucher for £3.95 off your next shop.
I love it for perfume samples, I just love trying new scents and also getting the smaller bottles which are great for traveling or just carrying in my handbag. I do tend to look for the more girthy sample sizes of skincare samples. Some of the Burts Bees ones have been super sizes.