Being such a meat lover, I am surprised that I hadn't visited Smithfield meat market sooner. Probably because i couldn't rope anyone into coming with me for a 4am visit!
If you like to buy in bulk, then this is the place. There are so many cuts to choose from here with most traders having similar prices, it can be quite overwhelming. You really need to have an idea of what prices are like at your local butcher or supermarket to be able to compare.
There is a variety of expensive cuts right down to cheap cuts like oxtail. I managed to get a 3kg bag of beef mince (5% fat) for £11 from PJ Martinelli. That will be a lot of burgers for the family!