If you look at the MLS Cup 2012 thread, there are pictures that are high-res enough for you to use as a wall. Just shrink and/or trim.
If you're looking to buy you can order from the MLS Photo Store - http://www.replayphotos.com/mlsphotostore/
Not really surprising given the quality of MLS refs. But come on dashiel, it's time to move on. Nothing good comes of living in the past.