Full list is here, best is to go through it and pick something suitable for your needs I think but here are a few that caught my eye.
SanDisk Cruzer Blade USB Flash Drive 16GB £7.49
Kingston Technology 16GB Data Traveler Champagne SE9 £10.69
Duracell Capless 32GB USB Memory Drive £17.49
Freecom 56145 DataBar 32GB £19.21
Make sure to select Amazon from the available sellers and if you spend £25 or more delivery is free.