i swear by my Rambo Horsewear flashing waist coat. i've had it 3 winters now and it is still going strong! i wear it on top of my hi-viz yellow coat and it reflects off the the coat - as a result i can be seen up to a mile away in the dark
You can get them from derby house/robinsons & frogpool i think & should be under 20.
I got one of these at YHL flashing tabbard It has flashing strips on the front and the triangle and horse on the back flash or can be lit without flashing. It is super bright.
I looked at those at YHL and to be perfectly honest, I thought the Rambo one was more effective - there is a wider area covered by lights front & back. I didn't think there was enough at the front for me to feel safe. Just my opinion though!!! Equisafety do a very good flashing breast plate (amongst a few other products http://www.equisafety.co.uk/) which is great, I also have 2 red cycle lights that i attach to the tail flap on my exercise rug & love the v-bandz leg wraps... I ride in the dark on the road or I don't get to ride so being visible is essential
I've got one but find the flashes ruin my night vision, what I have got off ebay is leg/arm bands that have either a flashing or just on setting which are good