I have found that rather than the price being the most important factor it is the quality and cut of the meat. The best I have found is a local butcher as they will cut exactly what you want and you can see it "in the flesh" before you hand over your money. Not all butchers are the same though. I went through 2 local butchers before I found the one that was right for me.
A couple of hints.
Cuts of meat like Brisket are generally smaller here than in the USA so give your butcher several days notice and tell him what you are going to do with it. He will be able to look out for a thick one for you and put it to one side. Also ask him not to roll it so you can see exactly what you are getting
Pork shoulder and leg should also be bought unrolled. The centre of a piece of rolled pork is a place where some butchers like to hide lots of fat. You are likely to smoke it open anyway so it just saves them the bother of tying it up.
Get to know your butcher and offer them samples. When on the odd occasion they hand over the meat and say "that will be £37.20 - Oh call it £35" then suddenly it does not seem quite so expensive.