I have a set of weight watchers scales that weigh in small amounts - mind you they are about 20 year old so not sure that they are still available - try looking on the website to see what they have now
Most modern digital scales would do. Some only go to 2 grams, you'd have to check before you make your choice. Try John Lewis and Lakeland websites. Mine is made by Salter, but isn't mini. It is "cool" looking, transparent with a glass platform.
Hana