Ortlieb Micro Two Saddlebag - 0.5 Litre From  £24.99

I got this saddlebag for my road bike. It's a bit smaller than the larger MIcro Two previously purchased for my touring bike but still easily fits two 700c tubes, tire levers, a small multitool and a small leatherman. The bonus is that the mounting hardware is the same for both Micro and larger saddle bags so I can swap in my 1.6 litre bag when I need to carry more.